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.