Black veins: a case of minocycline‐induced pigmentation post‐sclerotherapy and a review of literature

Minocycline‐induced pigmentation (MIP) is an uncommon but well‐described adverse effect of oral minocycline treatment. MIP is clinically and histopathologically distinct from post‐sclerotherapy pigmentation. We report a case of a patient presenting with blackened skin overlying veins recently treated with endovenous laser and foam sclerotherapy. The patient was a 44‐year‐old male with systemic sclerosis who commenced minocycline for the treatment of rosacea 5 months prior. Histological examination of the discolored tissue and underlying vein revealed hemosiderin deposition in the dermis and pigmented macrophages within the sub‐endothelial layer of the vein wall with a staining pattern consistent with MIP. Venous tissue has not previously been reported in the literature as a target of minocycline pigmentation. Our patient preferred to control his rosacea by continuing to take minocycline. Follow‐up ultrasound examinations revealed the treated vessels to be fully occluded with no evidence of recanalization, residual flow or ongoing thrombophlebitis. Despite a good sclerotherapy outcome, the pigmentation did not subside over 2 years. This case demonstrates that oral minocycline may induce significant and potentially long‐term pigmentation in predisposed patients undergoing sclerotherapy.