ENCAPSULATED COLUMNAR-CELL NEOPLASMS OF THE THYROID - A REPORT OF 4 CASES SUGGESTING A FAVORABLE PROGNOSIS

Four encapsulated thyroid neoplasms with columnar-cell features were s tudied. The patients were a 29-year-old man and three women aged 42, 6 0, and 83 years. The tumors measured from 1.2 to 8.0 cm in maximum dim ension. All were completely surrounded by a thick capsule; three demon strated invasion into the capsule (but no farther), whereas one (from the 60-year-old woman) did not. In addition to columnar-cell areas, al l the neoplasms had areas with follicular and solid growth, in varying proportions. Although the growth pattern in the columnar-cell zones w as usually papillary, nuclear characteristics of papillary carcinoma w ere not present in these areas or elsewhere. Follow-up on the four pat ients was 112, 51, 112, and 29 months, respectively, and none had any evidence of recurrence or metastasis. The findings suggest that encaps ulated columnar-cell thyroid tumors have a much more favorable prognos is than those that are unencapsulated and invasive into adjacent thyro id or extrathyroid tissue.