A clinicopathologic study of 241 cases of papillary thyroid carcinoma treated at the University of Florence Medical School, Florence, Italy is presented. The features of greatest prognostic value were patient's age at presentation, small tumor size, total encapsulation, extrathyroid extension, multicentricity, and presence of distant metastases. The prognosis of the disease was not influenced by the pattern of tumor growth, presence of solid areas, initial presence or subsequent development of cervical lymph node metastases, type of initial thyroid operation, performance of neck dissection, or prophylactic administration of radioactive iodine. It is concluded that conservative thyroid surgery in the form of lobectomy, without neck dissection or prophylactic administration of iodine 131 (131I), constitutes adequate therapy for most cases of papillary thyroid carcinoma. More extensive therapy should be considered for older patients and for those in whom the tumor exhibits extrathyroid extension or easily detectable multicentricity.

Seventy cases of anaplastic thyroid carcinomas studied at the Universities of Florence (Italy) and Minnesota are presented. Three morphologic patterns were seen: spindle, giant cell, and squamoid, sometimes in combination. Ultrastructurally, evidence of epithelial differentiation was seen in most but not all cases studied. Immunohistochemically, a stain for cytokeratin using a monoclonal antibody was found the most useful adjunct to diagnosis. Unexpected positivity for carcinoembryonic antigen (CEA) was found in several squamoid tumors. The alleged frequent positivity of this tumor type for thyroglobulin and calcitonin was not confirmed. A third of the tumors were associated with a better differentiated component, of which, presumably, they represented a dedifferentiation. The extremely aggressive behavior of anaplastic thyroid carcinomas was confirmed amply in this series: all of the patients in whom follow-up information was available died of their tumor. Small cell tumors should not be included into the anaplastic category, since they invariably belong to other groups, i.e., malignant lymphoma, medullary carcinoma, and poorly differentiated ("insular") carcinoma.

Comparison of our data with the literature showed many differences that could be related to different applied diagnostic criteria. We underlined the importance of histology as reproducible criterion for diagnosis of primary colorectal SRCC.

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