THYROID PAPILLARY CARCINOMA OF COLUMNAR CELL-TYPE - A CLINICOPATHOLOGICAL STUDY OF 16 CASES

BACKGROUND. Thyroid papillary carcinoma of columnar cell type is consi dered an uncommon histologic subtype of papillary carcinoma characteri zed by its morphologic features and purportedly aggressive biologic co urse. METHODS. Sixteen cases of thyroid papillary carcinoma of columna r cell type were identified from the Endocrine Tumor Registry at the F ilmed Forces Institute of Pathology and the Washington Hospital Center . Clinical records and follow-up were available in all cases, Paraffin blocks were available for histochemical and immunohistochemical studi es in 15 of the 16 cases. RESULTS. Of the 16 cases reported, 13 patien ts were female and 3 were male. The ages ranged from 16-76 years (aver age, 47 years; median, 40 years). An asymptomatic neck mass was the mo st common clinical presenting symptom. Macroscopically, the tumors var ied from circumscribed or encapsulated to infiltrative, ranging in siz e from 1.5-6.5 cm. Histologically, the tumors had diverse growth patte rns, including papillary, solid, microfollicular, and cribriform. A co mmon pattern was the presence of markedly elongated follicles arranged in parallel cords. Colloid-filled follicles could be found, at least focally, in all cases. The characteristic histologic appearance includ ed the presence of elongated cells showing nuclear stratification. Oth er features included the presence of vacuolated-appearing sells, spind le-shaped cells, and squamoid nests. Limited areas in the tumors showe d morphologic features typical of thyroid papillary carcinoma. In 14 o f the cases, the tumor was encapsulated, showed limited invasive growt h, or was a microscopic tumor. In two of the cases, there was extrathy roidal invasion. Immunohistochemical studies showed consistent reactiv ity with cytokeratin and vimentin; varied reactivity with thyroglobuli n, epithelial membrane antigen, carcinoembryonic antigen, and LeuM1; a nd no reactivity with calcitonin or chromogranin. Treatment was by sur gical resection; supplemental radioactive iodine therapy was administe red in eight patients. Follow-up was available for all patients, 13 of whom (81%) were alive and free of disease or had died of unrelated ca uses over periods ranging from 2-11 years (average, 5.8 years). All 13 of these patients had tumor confined completely to the thyroid gland. One patient died 4 months after diagnosis secondary to sepsis. Two pa tients (17%) had aggressive biologic courses. In both patients there w as extrathyroidal invasion. One of these patients died of metastatic d isease to the lungs 3 years after diagnosis; the other was alive with bilateral pulmonary metastases 9 years after the diagnosis. CONCLUSION S. The findings of the current study indicate that thyroid papillary c arcinoma of columnar cell type is a distinct morphologic type but not a distinct clinical type of thyroid papillary carcinoma, The biologic behavior of this tumor is predicated on clinical stage, with the prese nce or absence of extrathyroidal invasion being the single most import ant parameter. Treatment of patients with these tumors should be based on the clinical stage and not on the morphologic appearance. (C) 1998 American Cancer Society.