Specialties: Anatomic Pathology

Claudin-7 is a transmembrane protein involved in the formation of tight junctions between epithelial cells.¹ The Claudin family of proteins are involved in critical roles of cellular polarity, signal transductions, and have been implicated in the pathogenesis of various human neoplasms including chromophobe renal cell carcinoma. The identification between chromophobe renal cell carcinoma and oncocytoma is difficult by light microscopy, and yet important as chromophobe renal cell carcinoma is malignant, whereas oncocytoma is benign.² Anti-claudin-7 reactivity is seen in most chromophobe renal cell carcinomas, while it is rarely seen in oncocytomas, and only seen in a minority of clear cell renal cell carcinomas.^1,3 Therefore, anti-claudin-7 could be a useful immunohistochemical marker for the distinction and identification of chromophobe renal cell carcinoma.