Minocycline-induced black thyroid with black pigmentation of the thyroid cartilage, cricoid cartilage, and trachea found during reconstructive surgery for hypopharyngeal cancer.

Black thyroid is characterized by a rare pigment change observed almost exclusively in patients taking minocycline. We present the case of a 72-year-old man diagnosed with T3N3bM0 stage IVB hypopharyngeal squamous cell carcinoma who had been taking minocycline for approximately 18 months as a treatment for prurigo chronica multiformis. Initial treatment consisted of total pharyngolaryngoesophagectomy, bilateral neck dissection, total thyroidectomy, pharyngeal reconstruction using a free jejunal autograft, and creation of a permanent tracheostoma. During surgery, black discoloration of the thyroid and trachea was observed. Postoperative histological findings confirmed the black discoloration, with deposits of dark-brown, melanin-like granules observed in the thyroid, trachea, thyroid cartilage, and cricoid cartilage. Therefore, the black discoloration of the thyroid associated with the use of minocycline can extend to the thyroid cartilage, cricoid cartilage, and trachea. This information is important for surgeons to recognize in order to prevent unnecessary resection due to misdiagnosis.

Occult Papillary Thyroid Carcinoma without Detection of the Primary Tumor on Preoperative Ultrasonography or Postoperative Pathological Examination: A Case Report.

Herein, we report a case of an occult thyroid cancer that was not detected as a primary tumor on preoperative ultrasonography or postoperative pathological examination, although a diagnosis of papillary thyroid carcinoma metastasis was made owing to the presence of a mass in the right upper neck. Needle biopsy of the mass in the right upper neck revealed positive results for thyroglobulin and TTF-1 on immunostaining, and a papillary thyroid carcinoma was observed with papillary and follicular patterns. We suspected papillary thyroid carcinoma (T0N1bM0) or ectopic papillary thyroid carcinoma. Accordingly, we performed total thyroidectomy, central lymph node dissection, right lateral neck dissection, and resection of the superficial lobe of the right parotid. A postoperative pathological examination of 5-mm slices of the specimen revealed no primary tumor in the thyroid. However, a hyalinized image of the thyroid indicated that a micropapillary thyroid carcinoma might have spontaneously disappeared. As there was no normal thyroid tissue in the metastasis to the superior internal jugular lymph node, the tumor was unlikely to be an ectopic papillary thyroid carcinoma. Therefore, we made a diagnosis of a papillary thyroid carcinoma (pT0N1bM0). After surgery, we determined that the tumor belonged to a high-risk group of papillary thyroid carcinomas and a poor-prognosis group of symptomatic papillary thyroid microcarcinomas; accordingly, ablation was performed with 30 mCi iodine-131. There was no recurrence or metastasis 24 months after the first surgery.