Germ-line mutations of the adenomatous polyposis (APC) gene, responsible for familial adenomatous polyposis (FAP) were analyzed in 15 patients with FAP-associated papillary thyroid carcinomas: 13 had the mutation between codons 778 and 1309 (exon 15), 1 at codon 593 (exon 14), and 1 at codon 140 (exon 3). Therefore APC gene mutations clustered in the genomic area associated with congenital hypertrophy of the retinal pigment epithelium (CHRPE) (codons 463-1387). Ocular patches were documented in 12 patients. In particular, 4 of the 15 patients, all women with a mean age of 23.5 (range 20-32), were found during the study of 15 consecutive kindreds who had undergone systematic screening for extra-colonic manifestations. Three of them belonged to the same kindred and were asymptomatic. These four patients were also screened for loss of heterozygosity of APC in the thyroid tumoral tissue. No biallelic inactivation of the APC gene was found. In contrast, three of these four patients had activation of the ret-PTC oncogene. In particular, there was activation of the ret-PTC1 isoform, a chimeric gene resulting from fusion of a gene named H4 with the RET gene. On histologic examination, three of the four patients showed Hashimoto-like lymphocytic infiltration. Present data suggest that: (1) the incidence of FAP-associated thyroid cancer probably has been underestimated in the past; (2) intensive screening could detect a larger than expected number of thyroid carcinomas; (3) systematic screening is recommended in patients with ocular patches and genetic mutation in exon 15; (4) Hashimoto-like findings do not exclude carcinoma but are a frequent accompanying finding; (5) despite frequent multicentricity and early lymph node involvement, FAP-associated thyroid tumors seem to have an excellent prognosis, in particular those showing ret-PTC activation.

The findings suggest that the tumours were certainly papillary, at least in the present kindred. Further studies in different families are required for a better understanding of this peculiar tumour and of its biological behaviour.

No abstract

The authors report three siblings (two sisters and their aunt, aged 20, 22 and 36, respectively) with familial adenomatous polyposis (FAP) and papillary thyroid carcinoma. After diagnosis of FAP, a single, non palpable nodule was revealed in each patient by routine screening ultrasonography of the gland. The diagnosis of papillary carcinoma was made by fine-needle-aspiration biopsy of the nodules and confirmed by histologic examination of surgical specimens. A review of the literature reveals about 40 reports of such an association, that is considered not fortuitous. Nevertheless, in this family the association seems to be a distinctive, clinical feature of the syndrome, affecting three out of five members intensively screened for extracolonic lesions.

The authors report three siblings (two sisters and their aunt, aged 20, 22 and 36, respectively) with familial adenomatous polyposis (FAP) and papillary thyroid carcinoma. After diagnosis of FAP, a single, non palpable nodule was revealed in each patient by routine screening ultrasonography of the gland. The diagnosis of papillary carcinoma was made by fine-needle-aspiration biopsy of the nodules and confirmed by histologic examination of surgical specimens. A review of the literature reveals about 40 reports of such an association, that is considered not fortuitous. Nevertheless, in this family the association seems to be a distinctive, clinical feature of the syndrome, affecting three out of five members intensively screened for extracolonic lesions.