Systemic Contact Dermatitis — SCE Dermatology MCQ

Instant feedback + full explanation. One question, done properly.

HardInflammatory DermatosesSystemic Contact DermatitisSCE Dermatology

A 35-year-old woman presents with a pruritic eruption on her earlobes and around her umbilicus. Patch testing reveals nickel allergy. She also reports systemic symptoms (widespread dermatitis, GI symptoms) after eating nickel-rich foods. What is this phenomenon?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Systemic contact dermatitis from dietary nickel exposure

Systemic contact dermatitis (SCD) occurs when a contact allergen is ingested or absorbed systemically, triggering a widespread dermatitis in a previously sensitised individual. Nickel is the classic cause — nickel-sensitised patients may develop systemic dermatitis (widespread eczematous eruption, vesicular hand dermatitis) and occasionally GI symptoms after ingesting nickel-rich foods (chocolate, cocoa, beans, nuts, canned foods). A low-nickel diet may improve symptoms in some patients. The mechanism involves hapten-protein complex presentation to memory T cells in the gut/skin. Chromium and Balsam of Peru are other allergens causing SCD from dietary exposure. Oral nickel challenge testing can confirm the diagnosis.

Reference: BAD 2017 Contact Dermatitis; ESCD 2019