Abstract
We report the clinicopathological features and genetic alterations of a case with multiple papillary thyroid carcinomas associated with familial adenomatous polyposis (FAP) and Stage Ⅳ colon cancer. A 38-year-old woman underwent a total thyroidectomy for three lesions (20mm, 10mm, and 3mm in diameter) in the thyroid, one (10mm in diameter) of which had been diagnosed preoperatively as a papillary carcinoma based on cytology findings. Twelve months before the thyroidectomy, she had undergone a total colectomy and ileorectal anastomosis for Stage Ⅳ transverse colon cancer, since a complete response to oxaliplatin-based chemotherapy (modified FOLFOX6) for multiple liver metastases had been obtained. A pathological examination revealed that all the tumors were papillary thyroid carcinoma. Genetic analysis of the APC gene from a blood sample and the largest thyroid cancer tissue identified a germ-line mutation (C deletion at codon 1,483) and a somatic mutation (G deletion at codon 295), both of which were considered to form stop codons resulting in truncated products of the APC genes. These results suggest that the inactivation of both alleles of the APC gene might be associated with the development of thyroid cancer in patients with FAP. The patient has remained free from colorectal and thyroid cancer recurrence for 24 months since the thyroidectomy.
