Thyroid-like Follicular Renal Cell Carcinoma: An Emerging Entity

Thyroid-like follicular renal cell carcinoma is an extremely rare tumor. The tumors show a striking resemblance to well-differentiated thyroid follicular neoplasm but can be differentiated on immunohistochemistry due to lack of thyroglobulin and thyroid transcription factor 1 expression. Thyroid-like follicular renal cell carcinoma is seen in younger patients in the second to fourth decade with female preponderance. Most of the cases are asymptomatic or present with usual complaints of renal cell carcinoma such as flank pain, hematuria, or renal mass. Thyroid-like follicular renal cell carcinoma is a primary renal epithelial malignant tumor. The tumor is well encapsulated with follicular architecture comprising microfollicles and macrofollicles containing eosinophilic colloid-like material. Thyroid-like follicular renal cell carcinoma represents a rare histologic subtype of renal cell carcinoma with low malignant potential. According to the latest WHO classification 2022 of renal tumors, Thyroid like follicular renal cell carcinoma (TLFC) is put into emerging/provisional entities. These tumor types are still not part of the classification but are discussed in WHO.