A rationale for conservative management of microscopic papillary carcinoma of the thyroid gland: a clinicopathologic correlation of 90 cases.

Microscopic papillary carcinoma of the thyroid gland (MPC) measuring < or = 1.0 cm in diameter has a generally benign outcome, but is often overtreated with additional surgery. Ninety cases of MPC and 77 cases of nonmicroscopic papillary carcinoma of the thyroid gland (non-MPC) from 1970 to 1980 were retrieved from the Endocrine Registry of the Armed Forces Institute of Pathology (AFIP), Washington, D.C. Histologic features and patient follow-up were analyzed. Twenty-one patients with MPC had multifocal disease within the affected thyroid lobe, while a further 15 had either bilateral or intraglandular spread. Four of 10 patients who had additional surgery were found to have additional foci of tumor. Fourteen patients with lymph node metastases at initial surgery had no subsequent nodal metastases. All patients were either alive without disease or had died of unrelated causes after an average follow-up period of 17.3 years. Of the 77 non-MPC patients, 13 developed lymph node metastases or local recurrences, and one died of metastatic disease. Sixty-four of these patients were alive without evidence of disease after an average follow-up of 22 years. Present findings show that while MPC may present with perithyroidal lymph node metastases (15.56%), patients do not develop clinical tumors in the remaining thyroid tissue. Our experience indicates that close clinical follow-up without additional surgery is the preferable management for patients with MPC.