An Occult Follicular Carcinoma Thyroid Presenting as Solitary Dural Metastasis - Interesting Case Report

Thyroid cancer accounts for approximately 1% of all human cancers. Follicular carcinoma thyroid (FCT) is the second most common thyroid cancer after papillary carcinoma. Follicular carcinoma thyroid accounts for 10-15% of clinically evident thyroid malignancies. Follicular carcinoma thyroid commonly metastasize to lung and bone. Intracranial metastasis occurs in about only 1%. Follicular carcinoma thyroid very rarely manifests itself as a solitary dural metastatic lesion. Here we report a rare case of 50 year old female who presented initially with a solitary osteolytic dural mass mimicking a meningioma in CT/MRI and at surgery. Histopathological and immunohistochemical (IHC) examination of the resected intracranial mass revealed metastasis from occult follicular carcinoma thyroid. Retrospective sonographic guided aspiration cytology of thyroid revealed Follicular neoplasm and confirmed with histopathology after resection. This case is presented for its extreme rarity, unusual initial presentation, diagnostic importance of histopathology and immunohistochemistry for definitive diagnosis and prognosis.