[Synchronous association of Bellini collecting ducts and pyelic transitional cell carcinoma]

Bellini's collecting ducts carcinoma represent a subgroup within renal carcinoma with an incidence of 0.4 to 2% of all renal tumours. The collecting ducts share their embryological origin in Wölf's duct with the calices, renal pelvis and ureter. This common embryological origin could justify the association of carcinoma originated in the collecting ducts with transitional urothelial carcinoma. This paper contributes two patients with Bellini's collecting ducts carcinoma associated to "in situ" carcinoma and transitional papillar carcinoma in the adjacent renal pelvis respectively. The authors review the diagnostic, pathoanatomical and therapeutical aspects found in the literature. A high index of suspicion is required to diagnose a case of Bellini's carcinoma in the face of predominantly central-medullar renal solid lesions, with infiltrating growth that causes morphological changes in the excretory system without deforming the external renal outline. The authors highlight the value of immunohistochemical studies to reach a diagnosis, considering the natural history and the sombre prognosis of this uncommon renal neoplasia.