Endocrine Abstracts

Papillary thyroid carcinoma (PTC) is a malignant tumour of follicular cell origin that is characterized by a broad diversity of histological variants. A genesis of multifocal PTC may be explained by both intrathyroid tumour dissemination and multiple focuses of tumour origination. A combination of two different focuses of PTC characterized by various molecular alterations of tumour cells in one thyroid could be rarely occurred. Follicular variant has similar clinical behaviour and prognosis as classic papillary PTC. Columnar cell variant was initially defined as an aggressive lesion by Evans in 1986.

Here, we present a case review of concurrent follicular and columnar cell variants with molecular analysis of BRAF status in tumour cells of different PTC histotypes.

Female of 62 years old was admitted to the Medical Radiological Research Centre with complaints of pain in a right thigh. A tumour of right femoral bone was diagnosed by X-ray examination. A core tumour biopsy revealed metastasis of thyroid carcinoma that cells were immunopositive for thyroglobulin and TTF-1. Thyroid ultrasonography showed two nodular lesions in right lobe and isthmus. Histological study of the thyroid after thyroidectomy revealed follicular variant in isthmus and columnar cell variant of PTC in right lobe. Histological review of resected right femur with metastatic tumour showed columnar cell type of PTC. Molecular study of DNA extracted from two different tumours revealed wild type status of BRAF in follicular variant and BRAF^T1799A point mutation in columnar cell variant.

Columnar cell variant of PTC is more aggressive type of thyroid carcinoma in a patient with two concurrent PTC variants (follicular and columnar cell). In contrast with follicular variant columnar cell variant of PTC was characterized by distant bone metastases and BRAF^T1799A point mutation.