Thyroid-like Follicular Carcinoma of the Kidney
This is an exceedingly rare variant of renal cell carcinoma that mimics well-differentiated thyroid follicular carcinoma. It appears to be a low-grade tumor with most cases being discovered incidentally. The tumor shown here is composed of micro- and macrofollicles containing colloid-like eosinophilic material. The follicles are separated by moderate amount of stroma containing chronic inflammatory cells and cholesterol clefts.