Inflammatory Dermatoses Flashcards

Allergic contact dermatitis is mediated by which immunologic mechanism?

Answer: Type IV delayed-type hypersensitivity

Allergic contact dermatitis is a T-cell-mediated type IV delayed hypersensitivity reaction.

A linear vesicular eruption on an exposed forearm after a hike is most characteristic of contact dermatitis from what?

Answer: Urushiol (poison ivy/oak)

Linear streaks of vesicles from plant brush-past are classic for urushiol-induced (Rhus) contact dermatitis.

The gold-standard test to identify the causative allergen in allergic contact dermatitis is what?

Answer: Patch testing

Patch testing applies standardized allergens under occlusion and is read at 48 and 72-96 hours to detect delayed reactions.

The most common metal allergen causing allergic contact dermatitis, often from earrings and belt buckles, is what?

Answer: Nickel

Nickel is the leading contact allergen worldwide, frequently from jewelry, fasteners, and buckles.

How does irritant contact dermatitis differ immunologically from allergic contact dermatitis?

Answer: It is non-immunologic direct cytotoxic injury

Irritant contact dermatitis results from direct chemical or physical damage without a specific immune sensitization step.

Nummular dermatitis is best described by which morphology?

Answer: Coin-shaped eczematous plaques

Nummular (discoid) dermatitis presents as well-demarcated coin-shaped eczematous plaques.

Stasis dermatitis, an inflammatory dermatosis of the lower legs, results from what underlying process?

Answer: Chronic venous insufficiency

Stasis dermatitis arises from venous hypertension and edema causing eczematous changes on the medial lower legs.