Sarcomatoid transformation in chromophobe renal cell carcinoma is extremely rare.Gastrointestinal symptoms in renal cell carcinoma are rare and are often secondary to the tumor local growth. While these symptoms are essentially represented by gastrointestinal bleeding, symptoms related to colonic perforation are extremely rare. Only four cases have been described having such a direct invasion which was revealed by gastrointestinal bleeding and that all of them were clear cell- RCC type. No case of chromophobe renal cell carcinoma with direct colonic invasion witch was revealed by colic occlusion, perforation and secondary peritonitis has been found in the literature. Our case report provides more evidence that chromophobe renal cell carcinoma has a propensity to progress to a high-grade spindle cell malignancy with sarcomatoid features gaining an ability to invade other organs such as colon in our case.
We report a case of a pT4 stage renal cell carcinoma, chromophobe type of solid growth with high nuclear grade (Fuhrman grade 4), extensive sarcomatoid differentiation (60 %), and multifocal tumor necrosis. The sarcomatoid proliferation was invading the colon and reaching its submucosa. Anti-CD10, anti-EMA and anti-cytokeratin 7 immunostains have shown a diffuse and intense staining of the tumor cells.
The sarcomatoid transformation of chromophoberenal cell carcinoma is extremely rare. Its occurrence worsens the prognosis especially by locoregional aggressiveness.