Hyperpigmented Scar Due to Minocycline Therapy
A 20-year-old woman presented with a heavily pigmented scar on the left lower abdomen following excision of a benign compound nevus. Reexcision showed an organizing scar with pronounced hemosiderinlike pigment deposition and no residual melanocytic lesion. Results of further histopathologic workup showed positive staining with both Perls stain for iron and Fontana-Masson stain. These findings led to further questioning of the patient, which revealed a history of minocycline therapy—information that had not been provided during her initial evaluation. Hyperpigmented scars may result from minocycline ingestion. We present a review of the literature, with particular regard to the possible mechanisms of minocycline hyperpigmentation and the differential diagnosis of hyperpigmented scars.
Minocycline therapy should be included in the differential diagnosis of hyperpigmented scars. Careful history taking and even repeated questioning may be necessary to elicit an accurate medication history. The pigmentation is most likely due to a minocycline metabolite, bound to iron; Fontana-Masson positivity may result from the action of reducing agents other than melanin. Slow resolution of the pigment can be expected following discontinuation of the drug. Nevertheless, biopsy is indicated when, as in this case, an atypical pigmented skin lesion raises concerns about malignant melanoma.
