Case report of delayed metastasis from thyroid micropapillary carcinoma to the deltoid muscle in a patient with thyroglobulin elevated negative iodine scintigraphy (TENIS)

Abstract

Differentiated thyroid cancers are common but distant metastasis to the muscles is rare. We present a case of 64-year-old male who underwent thyroidectomy for a suspicious thyroid lesion. His histopathology was reported as widely invasive follicular carcinoma of the thyroid with a focus of micropapillary carcinoma (MPC). He underwent radioiodine ablation. On follow-up, he had a serial increase in thyroglobulin but a whole-body radioiodine scan failed to detect any lesion. An 18-fluorodeoxyglucose positron emission tomography (PET)-computed tomography scan picked up a lesion in the left deltoid muscle. An intraoperative ultrasound localization was done and the nonpalpable lesion was successfully removed surgically. The deltoid lesion was a delayed metastasis of a thyroid MPC. A rising thyroglobulin level in a patient with negative iodine scintigraphy warrants further evaluation with PET since rare distant metastasis may be present. A surgeon performing intraoperative ultrasound is useful in effectively identifying and removing occult lesions with small incisions.