Scurvy — SCE Dermatology MCQ

Correct answer: C — Impaired collagen hydroxylation from vitamin C deficiency

The correct answer is C, impaired collagen hydroxylation from vitamin C deficiency. This man has a classic scurvy triad: perifollicular haemorrhage, corkscrew hairs and gingival bleeding, in the context of alcohol dependence and a diet limited to toast and tea, which provides essentially no vitamin C. Ascorbic acid is a required cofactor for prolyl and lysyl hydroxylase, and without it, collagen cannot be properly hydroxylated and cross-linked, so small vessel walls and perifollicular connective tissue become fragile, producing the perifollicular bleeding and abnormal, coiled hair shafts. Vitamin C deficiency also impairs folate handling and dietary intake overall, which explains the coexisting macrocytic anaemia, and normal platelets and clotting screen confirm the bleeding is due to structural vessel fragility rather than a coagulopathy. Why the other options are wrong: E. Platelet dysfunction from aspirin use: there is no mention of aspirin, and platelet count and function would need to be abnormal, whereas here counts and clotting are explicitly normal. B. Autoantibodies against type VII collagen: this describes epidermolysis bullosa acquisita, which causes subepidermal blistering at trauma sites, not perifollicular haemorrhage or corkscrew hairs. D. Complement-mediated small-vessel vasculitis: vasculitic purpura is typically palpable, non-follicular and often affects the lower limbs, without the follicular hair changes seen here. A. Zinc deficiency affecting wound healing: zinc deficiency causes acral and periorificial dermatitis with alopecia, not perifollicular haemorrhage or corkscrew hairs, and does not explain macrocytic anaemia. Key point: perifollicular haemorrhage plus corkscrew hairs in a malnourished or alcohol-dependent patient is pathognomonic of scurvy from vitamin C deficiency impairing collagen hydroxylation.

Reference: RCEMLearning, Scurvy, 2023, https://www.rcemlearning.co.uk/foamed/scurvy/