Follicular Carcinoma Associated with Minocycline-Induced Black Thyroid.

Grossly evident black pigmentation of the thyroid has been observed in a number of patients, most of whom have a history of chronic ingestion of minocycline. In the majority of reported cases, no thyroid dysfunction or lesion has been noted, although rare instances of papillary carcinoma have been described. We describe a patient with a history of chronic minocycline ingestion, who presented with a neck mass of recent onset. Histologic examination of the thyroid revealed diffuse pigment deposition, typical for that seen in association with minocycline ingestion. Also present was a 3.2-cm follicular neoplasm with capsular and vascular permeation, consistent with minimally invasive follicular thyroid carcinoma. This represents the first report of follicular carcinoma associated with minocycline-induced black thyroid (MIBT).