AUTONOMOUSLY FUNCTIONING (HOT) NODULE OF THE THYROID-GLAND - A CLINICAL AND HISTOPATHOLOGIC STUDY OF 17 CASES

The authors present the clinical and pathologic findings of 17 patient s with autonomously functioning (hot) nodule of the thyroid (AFNT). Th e patients were 13 to 68 years of age, and 12 were female. Five had ob vious laboratory findings of hyperthyroidism, but the other 12 were eu thyroid. Fifteen patients had solitary or multiple benign nodules. The remaining two had autonomously functioning carcinomas; one of these p atients had a papillary carcinoma with no distant metastases, and the other had a follicular carcinoma with widespread metastases. Total thy roidectomy was performed in one patient, subtotal thyroidectomy was pe rformed in four, and hemithyroidectomy in eight. Diagnostic large need le biopsy was performed in only four patients. Of the 13 patients unde rgoing thyroidectomy, 3 had multiple hot nodules, and 10 had a solitar y hot nodule. The size of the nodules ranged from very small to 6 cm, with no definite correlation found between the size of the nodule and thyroid function. Pathologically, cystic change and hemorrhage to vari ous degrees were common features of AFNT. On histologic examination of the nodules, 13 were diagnosed as follicular adenoma (6 predominantly macrofollicular; 4 mixed micro-, normo-, and macrofollicular; and 3 p redominantly papillary) and 2 as adenomatous goiter (1 predominantly p apillary and 1 predominantly macrofollicular). The remaining two were diagnosed as carcinoma (1 follicular variant of papillary carcinoma an d 1 follicular carcinoma). Two children had benign nodules showing a p redominantly papillary architecture. Microcarcinoma outside the nodule s was found in two patients, and both microcarcinomas were a papillary type. The AFNTs showed characteristic pathologic findings, and the pa thologic differentiation of AFNTs from usually observed nonfunctioning (cold) nodules was not difficult. Pathologists should pay particular attention to AFNTs showing a papillary architecture, because these pap illary lesions are sometimes mistaken for papillary thyroid carcinoma.