Familial papillary thyroid cancer; A male case with breast and thyroid cancer and his three sisters with thyroid cancer: A case series and review of the literature.

Thyroid cancer is the most widespread endocrine malignancy. Of all the cases of thyroid cancer, approximately 95% arise from follicular cells. Familial non-medullary thyroid cancers constitute 3-9% of all the reported cases of thyroid cancer and are diagnosed by the presence of two or more first-degree relatives with cancer. Most familial cases of non-medullary thyroid cancer are caused by papillary thyroid cancer and its histological variants. Although some genes predisposing to familial papillary thyroid cancer have been identified, their functionality is unclear, and routine examination is not recommended. Some of these cases may be syndromic, but most cases (>95%) are non-syndromic. Various researchers have suggested an association between familial papillary thyroid cancers and earlier age of onset, higher multifocal tumor rate, extrathyroid enlargement, lymph node metastasis, and disease recurrence. Therefore, screening and close follow-up of other family members are essential when familial papillary cancer is diagnosed. This case report presents a familial papillary thyroid cancer series involving an index male patient with a breast cancer history and his three sisters with thyroid papillary cancer.