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Minocycline Pigmentation — RACP Adult Medicine MCQ

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ModerateRheumatologyMinocycline PigmentationRACP Adult Medicine

A 40-year-old woman on minocycline for acne for 3 years develops blue-grey pigmentation on her shins, old acne scars, and sclera. She has no systemic symptoms. LFTs and thyroid function are normal. What is the mechanism of pigmentation?

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Correct answer: E — Drug-induced melanosis

Blue-grey pigmentation in shins, scars, and sclera after prolonged minocycline use is drug-induced melanosis (type II minocycline pigmentation). Minocycline chelates iron and deposits in the dermis as an insoluble drug-iron complex. It is usually irreversible. Other drugs causing pigmentation include amiodarone (slate-grey), chloroquine, and heavy metals.

Reference: eTG Dermatology – 2024 – Drug-Induced Pigmentation; AMH 2025