Hydroxychloroquine induced cutaneous pigmentation: a unique pattern.

An elderly woman presented with 6 months history of skin coloured to erythematous papules in annular pattern over extremities, upper back and neck. The patient was diagnosed with granuloma annulare (GA) and started on hydroxychloroquine (HCQ) 300 mg daily. After 4 months of treatment, she developed bluish grey pigmentation within the plaques of GA with normal surrounding skin (figure 1A,B). There was no pigmentation at other body sites. Biopsy from the plaque showed necrobiotic collagen with intradermal mucin and perivascular lymphohistiocytic infiltrate accompanied by brown coarse pigment in the dermis …