Seborrheic Dermatitis

Epidemiology and Etiology

Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) is a common chronic skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disorder that is characterized by erythematous patches Patches Vitiligo with greasy, yellowish scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions that most often appear in areas with prominent sebaceous glands (scalp, face, upper trunk, and anogenital area).

Epidemiology

• Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: 3% of the general population
• More common in men
• Bimodal distribution Bimodal distribution Measures of Central Tendency and Dispersion: occurs in two peaks (first in infancy, then in adolescence and early adulthood)
• Up to 70% of infants < 3 months of age are affected but improvement noted by 1 year
• In adults, the disease peaks between the 3rd and 4th decades.

Etiology

Unclear, but may be affected by  the following:

• Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions colonization Colonization Bacteriology of Malassezia Malassezia Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Malassezia Fungi and its interaction with lipids Lipids Lipids are a diverse group of hydrophobic organic molecules, which include fats, oils, sterols, and waxes. Fatty Acids and Lipids on skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions surface
• Individual susceptibility:
  • Increased sebaceous gland Sebaceous Gland Small, sacculated organs found within the dermis. Each gland has a single duct that emerges from a cluster of oval alveoli. Each alveolus consists of a transparent basement membrane enclosing epithelial cells. The ducts from most sebaceous glands open into a hair follicle, but some open on the general surface of the skin. Sebaceous glands secrete sebum. Hordeolum (Stye) activity (seborrhea)
  • Stress
• Immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome:
  • HIV HIV Anti-HIV Drugs infection
    • Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) affects up to 85% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with AIDS AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS.
    • Severe seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with low CD4 counts
  • Lymphoma Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Imaging of the Mediastinum
  • Renal transplantation
• Neuropsychiatric conditions:
  • Parkinson’s disease 
    • Increased sebum Sebum The oily substance secreted by sebaceous glands. It is composed of keratin, fat, and cellular debris. Infectious Folliculitis production
    • Improvement of seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) with use of levodopa Levodopa The naturally occurring form of dihydroxyphenylalanine and the immediate precursor of dopamine. Unlike dopamine itself, it can be taken orally and crosses the blood-brain barrier. It is rapidly taken up by dopaminergic neurons and converted to dopamine. It is used for the treatment of parkinsonian disorders and is usually given with agents that inhibit its conversion to dopamine outside of the central nervous system. Parkinson’s Disease Drugs
  • Alzheimer’s dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders, depression
• Alcoholism Alcoholism A primary, chronic disease with genetic, psychosocial, and environmental factors influencing its development and manifestations. The disease is often progressive and fatal. It is characterized by impaired control over drinking, preoccupation with the drug alcohol, use of alcohol despite adverse consequences, and distortions in thinking, most notably denial. Each of these symptoms may be continuous or periodic. Wernicke Encephalopathy and Korsakoff Syndrome
• Climate changes (worse in cold temperatures, some improve with sun exposure)
• Medications:  lithium Lithium An element in the alkali metals family. It has the atomic symbol li, atomic number 3, and atomic weight [6. 938; 6. 997]. Salts of lithium are used in treating bipolar disorder. Ebstein’s Anomaly, haloperidol Haloperidol A phenyl-piperidinyl-butyrophenone that is used primarily to treat schizophrenia and other psychoses. It is also used in schizoaffective disorder, delusional disorders, ballism, and tourette syndrome (a drug of choice) and occasionally as adjunctive therapy in intellectual disability and the chorea of huntington disease. It is a potent antiemetic and is used in the treatment of intractable hiccups. First-Generation Antipsychotics, chlorpromazine Chlorpromazine The prototypical phenothiazine antipsychotic drug. Like the other drugs in this class chlorpromazine’s antipsychotic actions are thought to be due to long-term adaptation by the brain to blocking dopamine receptors. Chlorpromazine has several other actions and therapeutic uses, including as an antiemetic and in the treatment of intractable hiccup. First-Generation Antipsychotics, immunosuppressants Immunosuppressants Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. Immunosuppressants, psoralen Psoralen Melanoma, dopamine Dopamine One of the catecholamine neurotransmitters in the brain. It is derived from tyrosine and is the precursor to norepinephrine and epinephrine. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. Receptors and Neurotransmitters of the CNS antagonists

Pathophysiology

• The exact pathophysiologic mechanism remains unknown.
• Findings involve sebaceous glands and Malassezia Malassezia Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Malassezia Fungi colonization Colonization Bacteriology. Association is strongly suggested because antifungal Antifungal Azoles agents decrease Malassezia Malassezia Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Malassezia Fungi organisms and effectively treat the disease.
• Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) is found in areas with abundant sebaceous glands.
• Malassezia Malassezia Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Malassezia Fungi (lipophilic yeast Yeast A general term for single-celled rounded fungi that reproduce by budding. Brewers’ and bakers’ yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried. Mycology) on the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions interacts with sebum Sebum The oily substance secreted by sebaceous glands. It is composed of keratin, fat, and cellular debris. Infectious Folliculitis. Yeast Yeast A general term for single-celled rounded fungi that reproduce by budding. Brewers’ and bakers’ yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried. Mycology produce lipases Lipases An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. It is produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. Lipid Metabolism and phosphatases Phosphatases Oxazolidinones which cleave fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance from sebum Sebum The oily substance secreted by sebaceous glands. It is composed of keratin, fat, and cellular debris. Infectious Folliculitis → release inflammatory free fatty acids Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Acid-Base Balance → aberrant keratinocyte Keratinocyte Epidermal cells which synthesize keratin and undergo characteristic changes as they move upward from the basal layers of the epidermis to the cornified (horny) layer of the skin. Successive stages of differentiation of the keratinocytes forming the epidermal layers are basal cell, spinous or prickle cell, and the granular cell. Erythema Multiforme production →  abnormal stratum corneum Stratum corneum Skin: Structure and Functions  → inflammatory response stimulated → skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions eruption
• Other factors include oxidative stress Oxidative stress A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products. Cell Injury and Death and cell-damaging oxygen radicals.

Clinical Presentation

General features

• Pruritic, erythematous papules and plaques
• Easily detachable greasy scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions and yellow crusts
• Remits and relapses

Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) in infants

• Affected areas:
  • Head:
    • Scalp (“cradle cap”)
    • Eyebrows, eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis, nasolabial and retroauricular folds, and neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess
  • Trunk: umbilicus and intertriginous areas Intertriginous areas Malassezia Fungi (opposite of atopic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema), which spares the intertriginous areas Intertriginous areas Malassezia Fungi)
• Leiner disease:
  • Rare disease associated with complement (C5) deficiency
  • Generalized severe seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema)
  • Also with diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea and/or vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types, or failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive

Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) in adults

• Affected areas:
  • Scalp: dandruff/pityriasis sicca; fine, white, flaking scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions on the scalp
  • Face:
    • Eyebrows, glabella, eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis, sides of the nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal), nasolabial folds (opposite of lupus, which spares the nasolabial folds)
    • Mustache and beard areas; improves with shaving
  • Trunk:
    • Intertriginous areas Intertriginous areas Malassezia Fungi ( axilla Axilla The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. Axilla and Brachial Plexus: Anatomy, inframammary folds, anogenital region) 
    • Upper chest and back

Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with HIV HIV Anti-HIV Drugs

• In patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with CD4 counts < 400 cells/microL, lesions may be widespread and difficult to control.
• Seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) can be the initial clinical cutaneous marker for HIV HIV Anti-HIV Drugs/ AIDS AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS (sudden severe onset, atypical distribution of lesions or treatment resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing)
• May improve with antiretroviral therapy Antiretroviral therapy Antiretroviral therapy (ART) targets the replication cycle of the human immunodeficiency virus (HIV) and is classified based on the viral enzyme or mechanism that is inhibited. The goal of therapy is to suppress viral replication to reach the outcome of undetected viral load. Anti-HIV Drugs

Diagnosis

• Diagnosis is based on clinical findings.
• Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma can be used if the diagnosis is uncertain. Findings on biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma:
  • Superficial perivascular inflammatory infiltrate ( neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation, lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology)
  • Psoriasiform hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation
  • Parakeratosis Parakeratosis Persistence of the nuclei of the keratinocytes into the stratum corneum of the skin. This is a normal state only in the epithelium of true mucous membranes in the mouth and vagina. Actinic Keratosis (retention of nuclei in the stratum corneum Stratum corneum Skin: Structure and Functions)
  • Focal spongiosis
  • Yeast Yeast A general term for single-celled rounded fungi that reproduce by budding. Brewers’ and bakers’ yeasts are saccharomyces cerevisiae; therapeutic dried yeast is yeast, dried. Mycology species in the stratum corneum Stratum corneum Skin: Structure and Functions
• In HIV HIV Anti-HIV Drugs: more parakeratosis Parakeratosis Persistence of the nuclei of the keratinocytes into the stratum corneum of the skin. This is a normal state only in the epithelium of true mucous membranes in the mouth and vagina. Actinic Keratosis, increased inflammatory infiltrate, and less spongiosis

Management

General approach

• Avoid cold temperatures
• Discontinue medications that can trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation flares
• Treat associated comorbidities Comorbidities The presence of co-existing or additional diseases with reference to an initial diagnosis or with reference to the index condition that is the subject of study. Comorbidity may affect the ability of affected individuals to function and also their survival; it may be used as a prognostic indicator for length of hospital stay, cost factors, and outcome or survival. St. Louis Encephalitis Virus

Medical therapy

• Topical agents containing:
  • Selenium Selenium An element with the atomic symbol se, atomic number 34, and atomic weight 78. 97. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of glutathione peroxidase. Trace Elements sulfide: has antifungal Antifungal Azoles properties
  • Tar: decreases inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and has antifungal Antifungal Azoles properties
  • Sulfur: keratolytic and has antifungal Antifungal Azoles properties
  • Salicylic acid: keratolytic; softens thick scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions
  • Zinc Zinc A metallic element of atomic number 30 and atomic weight 65. 38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with anemia, short stature, hypogonadism, impaired wound healing, and geophagia. It is known by the symbol zn. Trace Elements pyrithione: has fungistatic Fungistatic Azoles and antibacterial Antibacterial Penicillins properties
• Antifungals:
  • Topical: ketoconazole Ketoconazole Broad spectrum antifungal agent used for long periods at high doses, especially in immunosuppressed patients. Azoles, naftifine, ciclopirox
  • Systemic ketoconazole Ketoconazole Broad spectrum antifungal agent used for long periods at high doses, especially in immunosuppressed patients. Azoles, fluconazole Fluconazole Triazole antifungal agent that is used to treat oropharyngeal candidiasis and cryptococcal meningitis in aids. Azoles, or itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles if refractory or with extensive disease 
• Topical steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors:
  • Only used for acute flares
  • Long-term use not recommended due to dermal atrophy Dermal Atrophy Secondary Skin Lesions and increased risk of recurrence and dependence
• Calcineurin inhibitors Calcineurin Inhibitors Compounds that inhibit or block the phosphatase activity of calcineurin. Immunosuppressants ( tacrolimus Tacrolimus A macrolide isolated from the culture broth of a strain of streptomyces tsukubaensis that has strong immunosuppressive activity in vivo and prevents the activation of T-lymphocytes in response to antigenic or mitogenic stimulation in vitro. Immunosuppressants, pimecrolimus Pimecrolimus Immunosuppressants) used as steroid alternatives, especially for delicate areas (e.g., face).
  • Suppress cytokine production
  • Do not have adverse effects of steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors

Differential Diagnosis

Differential diagnoses of seborrheic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema) include the following conditions:

• Atopic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema): chronic, relapsing, inflammatory skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disease that often precedes asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma and other allergic disorders. The main features of this skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions condition are intense pruritus Pruritus An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Atopic Dermatitis (Eczema) and eczematous skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions lesions.
• Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis: a chronic, recurrent, relapsing skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disorder characterized by inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and hyperproliferation of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions cells of the epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions. Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis presents with salmon-colored plaques with overlying silvery scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions, which is why this disease is also called plaque Plaque Primary Skin Lesions psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis.
• Impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo: an infectious condition characterized by bacterial infection of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions. Impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo can present with bullous or nonbullous lesions. The crusts in nonbullous impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo are honey-colored and located on the face and upper or lower extremities. Bullous impetigo Bullous Impetigo Impetigo, as the name implies, involves the formation of bullous skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions eruptions.
• Tinea versicolor Tinea versicolor A common chronic, noninflammatory and usually symptomless disorder, characterized by the occurrence of multiple macular patches of all sizes and shapes, and varying in pigmentation from fawn-colored to brown. It is seen most frequently in hot, humid, tropical regions and is mostly caused by Malassezia furfur (formerly Pityrosporum orbiculare). Malassezia Fungi: Malassezia Malassezia Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Malassezia Fungi furfur is the causative pathogen for this superficial infection of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, which presents with hypopigmentation Hypopigmentation A condition caused by a deficiency or a loss of melanin pigmentation in the epidermis, also known as hypomelanosis. Hypopigmentation can be localized or generalized, and may result from genetic defects, trauma, inflammation, or infections. Malassezia Fungi or hyperpigmentation Hyperpigmentation Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance. Malassezia Fungi of the infected area.
• Tinea capitis Tinea capitis Ringworm of the scalp and associated hair mainly caused by species of Microsporum; Trichophyton; and Epidermophyton, which may occasionally involve the eyebrows and eyelashes. Dermatophytes/Tinea Infections: infection of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions caused by the dermatophyte fungi Fungi A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including mushrooms; yeasts; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies. Mycology. There are 3 types of dermatophytes Dermatophytes Tinea infections are a group of diseases caused by fungi infecting keratinized tissue (hair, nails, and skin). These infections are termed dermatomycoses and are caused by the dermatophyte fungi. There are approximately 40 dermatophyte fungi that are part of 3 genera, including Trichophyton, Epidermophyton, and Microsporum. These infections can affect any part of the body but occur most often in warm, moist regions like the groin and the feet. Dermatophytes/Tinea Infections: trichophyton Trichophyton A mitosporic fungal genus and an anamorphic form of arthroderma. Various species attack the skin, nails, and hair. Dermatophytes/Tinea Infections, epidermophyton Epidermophyton A fungal genus which grows in the epidermis and is the cause of tinea. Dermatophytes/Tinea Infections, and microsporum Microsporum A mitosporic oxygenales fungal genus causing various diseases of the skin and hair. The species microsporum canis produces tinea capitis and tinea corporis, which usually are acquired from domestic cats and dogs. Teleomorphs includes arthroderma (nannizzia). Dermatophytes/Tinea Infections. 
• Pityriasis rosea Pityriasis rosea Pityriasis rosea is an acute, self-limited skin disease. The etiology is not known, and it commonly occurs in young adults. Patients initially present with a single, ovoid “herald patch.” This is followed by diffuse, pruritic, scaly, oval lesions over the trunk (often in a “Christmas tree” distribution on the back) and extremities. Pityriasis Rosea: a common skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions eruption that is characterized by a single skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions patch Patch Nonpalpable lesion > 1 cm in diameter Generalized and Localized Rashes that usually evolves into a widespread exanthem Exanthem Diseases in which skin eruptions or rashes are a prominent manifestation. Classically, six such diseases were described with similar rashes; they were numbered in the order in which they were reported. Only the fourth (Duke’s disease), fifth (erythema infectiosum), and sixth (exanthema subitum) numeric designations survive as occasional synonyms in current terminology. Varicella-Zoster Virus/Chickenpox after 1 week. The condition typically lasts 6 weeks and is self-limited, with an excellent prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas. 
• Candidiasis Candidiasis Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). Candida/Candidiasis: an opportunistic fungal infection that can affect the gastrointestinal tract or skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, or be systemic in immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship. Clinical presentation varies and is dependent on the severity of immunosuppression and the anatomical site affected. 
• Pemphigus vulgaris: a chronic, autoimmune, intraepithelial disease characterized by blister Blister Bullous Pemphigoid and Pemphigus Vulgaris formation involving the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions and mucous membranes. Caused by autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques, which are directed against target antigens present on the cell surface of keratinocytes Keratinocytes Epidermal cells which synthesize keratin and undergo characteristic changes as they move upward from the basal layers of the epidermis to the cornified (horny) layer of the skin. Successive stages of differentiation of the keratinocytes forming the epidermal layers are basal cell, spinous or prickle cell, and the granular cell. Skin: Structure and Functions.
• Secondary syphilis Secondary Syphilis Syphilis: untreated primary syphilis Primary Syphilis Syphilis becomes secondary syphilis Secondary Syphilis Syphilis. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with a generalized non-pruritic maculopapular Maculopapular Dermatologic Examination rash Rash Rocky Mountain Spotted Fever, generally on the palms and soles, along with pustular lesions. Various skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions lesions include condylomata lata Condylomata Lata Syphilis and white plaques.
• Scabies Scabies Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which presents most commonly with intense pruritus, characteristic linear burrows, and erythematous papules, particularly in the interdigital folds and the flexor aspects of the wrists. Scabies: highly contagious skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions infection caused by Sarcoptes scabiei Sarcoptes scabiei A species of mite that causes scabies in humans and sarcoptic mange in other animals. Specific variants of s. Scabiei exist for humans and animals, but many have the ability to cross species and cause disease. Scabies mites Mites Any arthropod of the subclass acari except the ticks. They are minute animals related to the spiders, usually having transparent or semitransparent bodies. They may be parasitic on humans and domestic animals, producing various irritations of the skin (mite infestations). Many mite species are important to human and veterinary medicine as both parasite and vector. Mites also infest plants. Scabies that are transmitted via direct physical contact. Scabies Scabies Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which presents most commonly with intense pruritus, characteristic linear burrows, and erythematous papules, particularly in the interdigital folds and the flexor aspects of the wrists. Scabies causes erythematous, pruritic papules, scattered vesicles Vesicles Female Genitourinary Examination, and thin, curvilinear burrow tracks.