Familial non-medullary thyroid carcinoma: pathology review in 27 affected cases from 13 French families

When familial non-medullary thyroid cancer (FNMTC) develops with no obvious associated pathogenetic factor, an inherited predisposition may underlie the process. The present study was conducted because detailed pathological findings are lacking in most series of FNMTC.

Thirteen families comprising 27 cases of FNMTC were included (1.8% of differentiated thyroid carcinoma). The family relationship (20 F, 7 M; age 46 +/- 16 years; mean +/- SD) was 'siblings' in eight families, 'parent and child' in four and 'aunt and niece' in one. Careful pathological review of the thyroid tumours (papillary/follicular: 25/2, size: 16 +/- 11 mm) was performed.

Initial staging according to extension was as follows: grade I (n = 16), II (n = 2), III (n = 6), IV (n = 3). Fourteen tumours were papillary microcarcinomas (size: 8 +/- 2 mm). No tumour phenotype that may be considered specific for FNMTC was found when considering either age, pathological findings or tumour aggressiveness. Although rare events were found in both relatives of some families suggesting a putative 'familial' phenotype of FNMTC, this may be fortuitous.

Micro familial non-medullary thyroid cancers are more common than previously reported and further studies are required to be able to distinguish this subgroup from sporadic papillary microcarcinomas. The careful pathological review of the familial non-medullary thyroid cancer in this study does not seem to point to a distinct subgroup of familial differentiated thyroid carcinoma although the data are intriguing. Genetic studies are now required to investigate this issue.