PATH - Miscellaneous skin disorders

Question 1

Acanthosis nigricans

Answer 1

Epidermal hyperplasia causing symmetric, hyperpigmented thickening of skin, especially in axilla or on neck

Associated with *insulin resistance or *visceral malignancy

Question 2

Actinic keratosis

Answer 2

*Premalignant lesions caused by sun exposure.

Small, rough, erythematous or brownish papule or plaques

Risk of *squamous cell carcinoma

Question 3

Erythema nodosum

Answer 3

*Painful inflammatory lesions of subcutaneous fat, usually on *anterior shins

associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, streptococcal infections, leprosy, inflammatory bowel disease

Question 4

Lichen Planus

Answer 4

6 P’s: Pruritic, Purple, Polygonal Planar Papules and Plaques

Mucosal involvement manifests as *Wickham striae (reticular white lines).

*Sawtooth infiltrate of
lymphocytes at *dermal-epidermal junction.

Associated with *hepatitis C.

Question 5

Pityriasis rosea

Answer 5

“Herald patch” followed days later by other scaly erythematous plaques, often in a “Christmas tree” distribution on trunk.

Multiple plaques with *collarette scale.

Self-resolving in 6–8 weeks.

Question 6

Sunburn

Answer 6

Acute cutaneous inflammatory reaction due to excessive UV irradiation.

Causes DNA mutations, inducing apoptosis of keratinocytes.

*UVB is dominant in sunBurn, UVA in tAnning and
photoAging.

Can lead to impetigo, skin cancers (basal cell carcinoma, squamous cell carcinoma,
melanoma).