Kidney, Clear cell papillary renal cell carcinoma, HMWK stain

Clear cell papillary renal cell carcinoma (RCC) is an important, recently described subtype of renal cell carcinoma that enters the differential diagnosis for many renal neoplasms. The typical features of this entity are that of a lesion comprised largely of papillary and tubular growth, which is lined by a low-grade population of cuboidal cells with clear cytoplasm. The importance of distinguishing this variant from other entities, such as clear cell RCC, is that it carries a favourable prognosis, with very low risk of recurrence or metastases post resection. Clear cell papillary RCC has a very specific immunohistochemical phenotype which allows confirmation of the diagnosis, with cells staining positive for CA9, CK7, and HMWK, and negative for CD10 and AMACR. This panel allows for confirmation of the diagnosis and the distinction of this entity from other renal neoplasms.

This slide shows HMWK stain. See Related Content for H&E, CA9, CK7, CD10, and AMACR stains.

See Related content for references:
1) Gobbo, S. et al. Am J Surg Pathol. 2008 Aug;32(8):1239-45
2) Williamson SR., et al. Mod Pathol. 2013 May;26(5):697-708