Characterized by tumor follicles filled with inspissated colloid-like materials.
All cases negative for thyroid markers (thyroglobulin- and TTF1-); metastatic thyroid primary carcinoma should be excluded before making the diagnosis.
Unclassified Renal Carcinomas
Primary renal carcinoma that does not fit to any of the known RCC types.
Mixture of RCC types (image A). (Except low-grade clear cell papillary RCC and TFE3 carcinoma with mixed clear cell and papillary growth).
Renal carcinoma with florid or pure sarcomatoid change that the original tumor is no longer identifiable (image B).