Soft Tissue Abscess

Overview

Definition

Soft tissue abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease is a collection of pus in the dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions or subcutaneous tissue.

Epidemiology

• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of abscesses rose throughout the 1990s; associated with an increase in methicillin-resistant Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess ( MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus).
• Since the 2000s, the incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of abscesses has plateaued.
• Abscesses can develop anywhere, but commonly are seen on the trunk, extremities, underarms, and buttocks.

Etiology

Causative agents:

• S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus (75% of cases):
  • Methicillin-sensitive S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus (MSSA)
  • MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus
• Polymicrobial:
  • S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus
  • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pyogenes
  • Gram-negative bacilli Bacilli Shigella
  • Anaerobes Anaerobes Lincosamides 
• Rare organisms:
  • Mycobacteria Mycobacteria Mycobacterium is a genus of the family Mycobacteriaceae in the phylum Actinobacteria. Mycobacteria comprise more than 150 species of facultative intracellular bacilli that are mostly obligate aerobes. Mycobacteria are responsible for multiple human infections including serious diseases, such as tuberculosis (M. tuberculosis), leprosy (M. leprae), and M. avium complex infections. Mycobacterium
  • Nocardia Nocardia Nocardia is a branching, filamentous, gram-positive bacilli. It is partially acid fast due to the presence of mycolic acids in the cell wall. Nocardia is a ubiquitous soil organism that most commonly affects immunocompromised patients. Nocardia is transmitted via inhalation of aerosolized bacteria or less commonly, via direct contact with wounds. Nocardia/Nocardiosis
  • 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 ( cryptococcus Cryptococcus Cryptococcosis is an opportunistic, fungal infection caused by the Cryptococcus species. The principal pathogens in humans are C. neoformans (primary) and C. gattii. Cryptococcus neoformans is typically found in pigeon droppings and acquired by inhaling dust from contaminated soil. The majority of affected patients are immunocompromised. Cryptococcus/Cryptococcosis, blastomycosis Blastomycosis Blastomycosis is an infection caused by inhalation of the spores of the fungus, Blastomyces. Blastomyces species thrive in moist soil and decaying material and are common in the Ohio and Mississippi River valleys and the Great Lakes regions of the United States and Canada. Although most patients are asymptomatic, some can develop pneumonia. Blastomyces/Blastomycosis)
• Sterile Sterile Basic Procedures: from injecting irritant drugs

Risk factors:

• Loss 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 integrity due to:
  • Trauma (e.g., abrasions Abrasions Corneal Abrasions, Erosion, and Ulcers) 
  • 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 (e.g., atopic dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema))
  • IV drug use
• Immunosuppression (e.g., diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus)
• Pre-existing 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 (e.g., folliculitis)
• Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity 
• MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus colonization Colonization Bacteriology
• Venous insufficiency
• Lymphedema Lymphedema Edema due to obstruction of lymph vessels or disorders of the lymph nodes. Lymphatic Filariasis (Elephantiasis)   

Pathophysiology and Clinical Presentation

Pathophysiology

• Break in 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 barrier → introduction of infection/causative agent
• Local cell injury Cell injury The cell undergoes a variety of changes in response to injury, which may or may not lead to cell death. Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Cell Injury and Death and necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage causes release of cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response.
• Inflammatory cells are drawn to the source of infection/irritation.
• Encapsulation by surrounding cells:
  • Prevents the spread of infection
  • Also inhibits penetration Penetration X-rays by immune cells and antibiotics, however
• Infection in a closed space (e.g., blocked sweat gland or perianal gland, hair follicle Hair follicle A tube-like invagination of the epidermis from which the hair shaft develops and into which sebaceous glands open. The hair follicle is lined by a cellular inner and outer root sheath of epidermal origin and is invested with a fibrous sheath derived from the dermis. Follicles of very long hairs extend into the subcutaneous layer of tissue under the skin. Cowden Syndrome) also facilitates abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease development.
• Low pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance inside the abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease cavity further decreases antibiotic effectiveness.

Clinical presentation

• Swelling Swelling Inflammation or discrete nodule Nodule Chalazion:
  • Tender 
  • Fluctuant Fluctuant Dermatologic Examination 
  • Erythematous 
• Surrounding induration Induration Dermatologic Examination
• +/- Streaking redness Redness Inflammation
• +/- Regional lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy 
• +/- Spontaneous purulent drainage
• Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways typically improves when the nodule Nodule Chalazion begins to drain.
• Systemic symptoms:
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Malaise Malaise Tick-borne Encephalitis Virus
  • Chills Chills The sudden sensation of being cold. It may be accompanied by shivering. Fever 
  • Sweats

Diagnosis

Soft tissue abscesses are usually diagnosed based on exam and history.

Laboratory studies

• Not needed in routine cases
• CBC may show leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus.
• ↑ Inflammatory markers (erythrocyte sedimentation rate, C-reactive protein)
• Blood and wound cultures obtained if:
  • Severe systemic manifestations
  • Presence of extensive cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis
  • Extremes of age
  • Recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID)
  • Failure of initial antibiotics
  • Immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome (e.g., neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia, diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus)
  • Special circumstances (animal bite, unusual exposure)

Imaging studies

• Not needed if abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease is obvious on physical exam
• Ultrasonography: shows hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography) mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
• CT scan with contrast if:
  • Worried about more extensive cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis or necrotizing fasciitis Necrotizing fasciitis Necrotizing fasciitis is a life-threatening infection that causes rapid destruction and necrosis of the fascia and subcutaneous tissues. Patients may present with significant pain out of proportion to the presenting symptoms and rapidly progressive erythema of the affected area. Necrotizing Fasciitis
  • Abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease shows up as a rim-enhancing lesion.

Management

Uncomplicated cases

• Incision and drainage Incision And Drainage Chalazion are the mainstay of treatment.
• If abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease is > 5 cm, packing of abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease cavity may help to keep it open and draining.
• Adjunctive oral antibiotics for 7–14 days should be considered:
  • For abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease > 2 cm
  • Multiple abscesses
  • Immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome/medical 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
  • Systemic symptoms ( fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children)
  • Prosthetic valve (risk of endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis)
  • Other prosthetic devices (e.g., prosthetic joints, vascular grafts)
• Antibiotics with staphylococcal and streptococcal coverage:
  • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim/ sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim
  • Cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with “cef-” or “ceph-.” Cephalosporins 
  • Clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides
• Adjunctive measures:
  • Elevation of affected extremity to ↓ swelling Swelling Inflammation
  • Warm compresses Warm Compresses Chalazion (to promote drainage)
  • Symptomatic fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever and pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways management

Cases requiring hospitalization Hospitalization The confinement of a patient in a hospital. Delirium and IV antibiotics

• Very large abscesses with extensive cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis
• Severe presentation: bullae Bullae Erythema Multiforme/blistering, skin necrosis Skin Necrosis Rocky Mountain Spotted Fever, signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
• Elderly
• Infants
• Significant immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome/poorly controlled diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
• Failure to improve with oral antibiotics
• IV antibiotics:
  • Streptococcal and staphylococcal coverage
  • Cefazolin Cefazolin A semisynthetic cephalosporin analog with broad-spectrum antibiotic action due to inhibition of bacterial cell wall synthesis. It attains high serum levels and is excreted quickly via the urine. Cephalosporins, ceftriaxone Ceftriaxone A broad-spectrum cephalosporin antibiotic and cefotaxime derivative with a very long half-life and high penetrability to meninges, eyes and inner ears. Cephalosporins, cefepime Cefepime A fourth-generation cephalosporin antibacterial agent that is used in the treatment of infections, including those of the abdomen, urinary tract, respiratory tract, and skin. It is effective against pseudomonas aeruginosa and may also be used in the empiric treatment of febrile neutropenia. Cephalosporins, or clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides
• Surgical management:
  • Drainage is still the mainstay of treatment.
  • May need to be done in the operating room under general anesthesia General anesthesia Procedure in which patients are induced into an unconscious state through use of various medications so that they do not feel pain during surgery. Anesthesiology: History and Basic Concepts 
  • Tissue debridement Debridement The removal of foreign material and devitalized or contaminated tissue from or adjacent to a traumatic or infected lesion until surrounding healthy tissue is exposed. Stevens-Johnson Syndrome may be required:
    • For extremely large or deep abscesses with tissue necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage
    • Skin necrosis Skin Necrosis Rocky Mountain Spotted Fever

Differential Diagnosis

• Cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis: a common and painful bacterial 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 that affects the deeper layers of dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions and subcutaneous tissue. Presents as an erythematous, edematous area that feels warm and tender to the touch. Caused most commonly by S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus and S. pyogenes. Diagnosis is usually clinical and management is with antibiotics based on suspected organisms.
• Necrotizing fasciitis Necrotizing fasciitis Necrotizing fasciitis is a life-threatening infection that causes rapid destruction and necrosis of the fascia and subcutaneous tissues. Patients may present with significant pain out of proportion to the presenting symptoms and rapidly progressive erythema of the affected area. Necrotizing Fasciitis: a rapidly progressive infection resulting in extensive necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage of subcutaneous tissue, fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis, and muscle. Most commonly caused by group A Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus but often involves other types of bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology in a mixed infection. Presents with necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage, crepitus Crepitus Osteoarthritis, bullae Bullae Erythema Multiforme, and purple 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 discoloration. Management is emergent surgical debridement Debridement The removal of foreign material and devitalized or contaminated tissue from or adjacent to a traumatic or infected lesion until surrounding healthy tissue is exposed. Stevens-Johnson Syndrome with broad-spectrum Broad-Spectrum Fluoroquinolones antibiotics.
• Dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema): a general term for an edematous 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 rash Rash Rocky Mountain Spotted Fever. Caused by an infection or an allergic reaction, usually not by bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology. Diagnosis is established clinically. Management is with antihistamines Antihistamines Antihistamines are drugs that target histamine receptors, particularly H1 and H2 receptors. H1 antagonists are competitive and reversible inhibitors of H1 receptors. First-generation antihistamines cross the blood-brain barrier and can cause sedation. Antihistamines and 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.
• Folliculitis: a localized 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 of the hair follicle Hair follicle A tube-like invagination of the epidermis from which the hair shaft develops and into which sebaceous glands open. The hair follicle is lined by a cellular inner and outer root sheath of epidermal origin and is invested with a fibrous sheath derived from the dermis. Follicles of very long hairs extend into the subcutaneous layer of tissue under the skin. Cowden Syndrome or sebaceous glands that is primarily caused by S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus. Presents as erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion, papules, pustules, and tenderness of the affected area. Diagnosis is made clinically, and treatment involves antibiotic 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 cleansers and, sometimes, systemic antibiotics.
• 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: a 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 of the upper 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. Caused by S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus or group A Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus. Presents with an erythematous area covered in small vesicles Vesicles Female Genitourinary Examination, pustules, and/or honey-colored crusts. Management is with antibiotics.
• Staphylococcal scalded skin syndrome: a blistering skin disorder caused by a local infection usually due to S. aureus. Presents with fever and diffuse, tender erythema, intraepidermal blisters, and sloughing off of the superficial layer of skin, leaving a red, “scalded” appearance. Management involves IV antibiotics.
• Epidermoid cyst: the most common cutaneous cyst, usually presenting as a skin-colored dermal nodule Nodule Chalazion, sometimes with a central punctum. Diagnosed clinically and treated with surgical excision or observation. Can become secondarily infected and turn into an abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease, in which case the cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change present as tender, erythematous, fluctuant Fluctuant Dermatologic Examination nodules, often spontaneously draining. 
• Hidradenitis suppurativa Hidradenitis suppurativa Hidradenitis suppurativa (HS) is a chronic skin condition due to the inflammation of apocrine sweat glands and hair follicles. Most commonly, it occurs due to occlusion of the follicular component of pilosebaceous units (PSUs). Hidradenitis Suppurativa: chronic suppurative infection of sweat glands manifesting primarily in the intertriginous areas Intertriginous areas Malassezia Fungi (axillae, groins, inframammary folds). Hidradenitis suppurativa Hidradenitis suppurativa Hidradenitis suppurativa (HS) is a chronic skin condition due to the inflammation of apocrine sweat glands and hair follicles. Most commonly, it occurs due to occlusion of the follicular component of pilosebaceous units (PSUs). Hidradenitis Suppurativa usually presents as cutaneous nodules and induration Induration Dermatologic Examination often associated with multiple draining sinuses. Diagnosis is established clinically and treatment involves antibiotics and surgical excision.