Thyroid-Like Follicular Carcinoma of the Kidney With Oncocytic Cells: A Case Report and Review of Metastatic and Non-metastatic Tumors.

Thyroid-like follicular carcinoma of kidney (TLFCK) is a morphological subtype of renal cell carcinoma, which is included as an emerging/provisional entity in the classification of renal tumors, with only about 40 cases reported in literature. It has a distinct histological appearance and immunohistochemical profile as compared with other renal cell cancers. However, these tumors, while appearing distinctive, have not been characterized fully either morphologically or by ancillary techniques. The reported cases show variable demographical and clinical features. Most are indolent, while some present with metastasis. The histological, immunohistochemical, and ultrastructural features of a case of TLFCK with clusters of oncocytic cells and pseudosarcomatous stroma are presented. Follow-up of 5 years was uneventful. A review of literature to analyze features in metastatic as compared with non-metastatic TLFCK is discussed. We report a patient of TLFCK and compare the clinicopathological features of metastatic and non-metastatic tumors.