Nuclear DNA content of medullary thyroid carcinoma in a large family with the MEN-2A syndrome.

Flow cytometry of medullary thyroid carcinoma (MCT) was performed in a large family with the MEN-2A syndrome. Of 15 family members with MCT five patients (10-27 yr) were without lymph node metastases. Six patients had a normal pentagastrin test after operation. All patients are alive and free of symptoms of MCT 6-9 yr after total thyroidectomy and an ablative dose of 131-I. In 12 of the 15 patients with MCT flowcytometry of paraffin-embedded tissue could be performed. The majority of all tumors (n = 9) were classified as peridiploid. Metastatic tumor, 6 years after thyroidectomy, in one of the patients was diploid. Only two MCT were clearly aneuploid. In one patient the tumor was tetraploid. We conclude that the majority of the MCT patients in this family with the MEN-2A syndrome have no or limited ploidy aberrations in their tumors, which correlates well with the favourable prognosis of familial MCT.