Kidney in VHL disease: Early clear cell proliferation occurs in the distal tubular system.

Renal clear cell carcinoma commonly occurs in patients with von Hippel‑Lindau disease (VHL). Kidneys of VHL disease patients (VHL kidneys) contain an abundance of independent clear cell proliferation events that have been hypothesized to represent precursor structures of clear cell carcinoma. In the present study, it was tried to identify the site of origin of clear cell proliferation, and the immunophenotype of clear cells. Using 3D histological tracking, the topographic origin of microscopic clear cell proliferation was investigated by identification of informative structures of interest and immunohistochemical staining for cluster of differentiation 10 (CD10) and cytokeratin 7 (CK7) in consecutive serial sections. In addition, the CD10/CK7 immunophenotype of proliferating clear cells was evaluated. Clear cell proliferation uniformly occurred in the distal tubular system. Some clear cell proliferation, however, revealed proximal tubule immunophenotype. It was concluded that early proliferation of VHL‑deficient clear cells occurs in the distal tubular system. Despite the association with the distal tubular system, the immunohistochemical profile of early clear cell proliferation may be inconsistent with its distal tubular origin.