Pathology - Skin

• chronic inflammatory disease with recurrent red or silvery plaques and scales. Munro micro-abscesses within the epithelium. Generally non-pruritic—elbows, knees, scalp, lower back
• Psoriasis may be associated with a severe rheumatoid arthritis especially of the fingers (psoriatic arthritis)

Superficial skin infection (Staph or Strep) presenting as superficial pustules with yellow crusts; most commonon the face and arms of children

Abscesses within the confines of hair follicles (usually caused by Staph). Confluent furuncles are called carbuncles.

redness of skin overlying an Strep infection in the subcutis—usually spreads along lymphatics

acquired loss of melanocytes producing areas of de-pigmentation (white patches); may be autoimmune origin

benign tumor or hamartoma; derived from melanocytes

Dark pigmentation usually in flexural areas of skin; can have oral pigmentation; sometimes a marker for internal malignancy such as GI, lung, breast, uterine cancer.

generally have the poorest prognosis of all melanomas, since they begin with a vertical growth phase.

The most common skin malignancy

• (Also called: Age spots; liver spots; senile lentigo)
• Brown macule on the skin larger than a freckle; found in 90% of Caucasians over age 40
• Well demarcated but with irregular borders
• Usually multiple
• Unlike freckles, these do not darken with continued sun exposure
• Results from chronic UV exposure
• Not pre-malignant

• Autoimmune condition characterized by loss of melanocytes and de-pigmentation of tissue in affected area.
• Treatment: cosmetic tanning creams and cover-ups; rarely responsive to steroids

• "mask of pregnancy"
• Acquired pigmentation noted during pregnancy and by women on birth control pills. 10% in men; sunlight plays important role
• Well-demarcated symmetric brown pigmentation—usually on face
• TMT: bleach creams

• Acute superficial cellulitis characterized by marked lymphatic vessel involvement
• Due to Strep (most commonly) or occasionally a Staph infection through a break in the skin
• Clinical: Dusky red, shiny , warm skin that is edematous and often indurated with a sharp border; high fever, malaise, leukocytosis
• Occurs in infants, small children, and elderly; typically self-limited (7-10 days)

• ―skin tag‖---soft flesh-colored pedunculated benign skin tumors
• More common around eyelids, armpits, and neck
• Remove with a scissors, preferably a sharp pair!

• Yellowish plaques, papules, or macules that may or may not be associated with hyperlipidemia
• Upper eyelids most common location

• Common viral skin disease presenting with discrete skin colored or white papules
• Transmitted by direct contact---especially daycare settings or schools
• Lesions develop 2-3 months after inoculation; asymptomatic
• Resolves spontaneously
• Histopathology: Molluscum bodies (Henderson-Patterson bodies)
• Treatment: – Cryotherapy – Laser – Aldara has mixed results
• Typically will resolve spontaneously in 6-12 months

• The most common benign tumor in older individuals—can be confused with a melanoma
• Light brown to black dark skin plaques occurring in middle age and older patients
• Stuck-on appearance with greasy feeling keratotic crust
• Surface may be rough or warty, can itch or become irritated
• Remove or treat if cosmetically objectionable – Liquid nitrogen – Shave biopsy – Alpha-hydroxy acids

• Whitehead: ―closed comedo‖---plugged follicule which does not communicate with the surface ( keratin, sebum, and bacteria)
• Blackhead: ―open comedo‖ collection as above but communicates with the surface

Inflammation of hair follicle usually by Staph or Candida (in perioral areas)

• Boil—deep erythematous painful fluctuant nodule proceeded by Staph folliculitis
• Usually occurs in areas of heavy perspiration or friction
• Treatment: Moist heat, may need incision and drainage as well as oral antibiotics

heat rash

• Transient papule or plaque formed by serum exudation into the dermis
• Caused by histamine release from mast cells and basophils
• Usually due to allergy

angular cheilitis

• Common skin disease affecting about 2% of the population; most commonly appears in young adulthood
• Unknown cause—strongly linked to heredity – Defect in control of keratinocyte proliferation (up to 8x normal turnover rate)
• Triggered by stress, systemic infections, drugs, skin trauma (Koebner’s phenomenon)
• Clinical: well defined erythematous plaque covered by silvery scales
• When scales are removed, pinpoint bleeding is seen (Auspitz sign)
• Oral lesions rare—appear as migratory glossitis
• In a small number, polyarthritis is noted
• Histo pathology: – Acanthosis (thickening of epithelium) – Parakeratosis – Neutrophils in aggregates in the epithelium: Munro’s microabscesses
• Treatment: – Topicals (tars, corticosteroids) – Systemic (methotrexate, retinoids) – PUVA (photochemotherapy)

• Acute superficial bacterial infection of the skin caused by Group A strep, Staph aureus, or both
• Highly contagious, common in children or adolescents; scratching causes spread to other sites
• Initial lesion is a small vesicle on the face with additional vesicles extending periorally and along the base of the nose
• Treatment: Bactroban; Penicillinase stable antibiotics