Cholestatic Pruritus — SCE Dermatology MCQ

Correct answer: B — Cholestatic pruritus from hepatic dysfunction with elevated bile salts

The correct answer is B, cholestatic pruritus from hepatic dysfunction with elevated bile salts. In chronic hepatitis C with cirrhosis, impaired hepatic function leads to cholestasis and retention of bile acids and other pruritogens (such as lysophosphatidic acid and endogenous opioids) that stimulate cutaneous itch fibres directly, without producing a primary rash. This explains why the pruritus is generalised and disproportionate to the visible skin findings, which here are only secondary excoriations from scratching rather than a true dermatosis. Cholestatic itch is a recognised systemic cause of pruritus that should be considered whenever itching occurs in the absence of an adequate primary skin explanation, particularly in a patient with known liver disease. Why the other options are wrong: C. Dermatophyte infection: this causes a localised, scaly, annular rash with a well demarcated active edge, not widespread symmetrical papules and excoriations, and would not be linked mechanistically to cirrhosis. A. Scabies: causes intense itch but typically with burrows in finger webs, wrists and genitalia, contacts with similar symptoms, and a primary dermatosis; it does not explain itch specifically disproportionate to skin findings in a cirrhotic patient. E. Drug-induced pruritus: no causative drug history is given in the stem, so this cannot be inferred as the mechanism when a clear hepatic cause is present. D. Allergic dermatitis: would produce a visible eczematous or urticarial primary dermatosis proportionate to symptoms, whereas here the pruritus is explicitly out of proportion to any primary lesion. Key point: Generalised pruritus that is disproportionate to visible skin disease in a patient with chronic liver disease points to cholestatic itch from bile salt and pruritogen accumulation, not a primary dermatosis.

Reference: British Journal of General Practice, 'Itch and liver: management in primary care', 2015, https://bjgp.org/content/65/635/e418