MACROFOLLICULAR VARIANT OF PAPILLARY THYROID-CARCINOMA - A CASE AND CONTROL ANALYSIS

The planimetric, flow cytometric, and immunohistochemical characterist ics of the macrofollicular variant of papillary thyroid carcinoma (MFV PTC) have not been reported before. The clinical, morphological, immun ohistochemical, planimetric, and flow cytometric characteristics of si x cases of the MFVPTC and six of the follicular variant of papillary t hyroid carcinoma (FVPTC) were analyzed. Patients had undergone surgica l treatment, The mean age was 38 (range 29-64 yr), and five were women . Tumors had a mean size of 3.2 cm (range 0.3-4.5 cm). Half were origi nally diagnosed as goiter. Macrofollicles had a mean diameter of 345.5 mu m, perimeter of 1237 mu m, and area of 13,779 mu m(2), with nuclea r changes of PTC. Mean follow-up was 107 mo (range 12-277), and neithe r lymph node metastases nor recurrence were seen. Differences in diame ter, perimeter, and area between the macrofollicular and follicular va riants were found. Follicular neoplastic cells were thyroglobulin and S-100 protein positive in macrofollicles and normofollicles. All were negative to cytokeratin and to high-mol-wt keratin. All tumors were di ploid. There were no significant differences in follow-up, DNA content , nor immunohistochemical reactivity. Differences in diameter (p < 0.0 0006), perimeter (p < 0.0001), and area (p < 0.001) were observed. It is important to recognize this variant because it could be misdiagnose d as benign thyroidal lesions.