A case of minocycline-induced black thyroid associated with papillary carcinoma

We report a rare case of black thyroid accompanied by papillary carcinoma in a patient with an extended history of minocycline treatment. A 78-year-old man was referred to our outpatient clinic with swelling in his neck. He had been taking minocycline for the previous 2 years and 7 months to treat chronic perianal pyoderma. Neck ultrasonography and computed tomography demonstrated a 3.5 × 3.7 × 5.0-cm nodule in the left thyroid lobe, and fine-needle aspiration cytology identified it as a papillary carcinoma. The patient underwent a total thyroidectomy and neck dissection. During the procedure, a distinct black discoloration of the thyroid parenchyma was observed. Histopathology confirmed both the black thyroid and the papillary carcinoma. Based on the thyroid gland's discoloration and the history of minocycline use, the patient was diagnosed with minocycline-induced black thyroid. He was symptom-free 20 months after surgery.