Which term describes a kidney cancer where the cells appear clear under the microscope?

• A. Papillary carcinoma
• B. Oncocytoma
• C. Clear cell carcinoma
• D. Chromophobe carcinoma

Answer: (C)

Think about what “clear” means in tissue anatomy. When kidney cancer cells look clear under the microscope, that clear appearance comes from the cytoplasm being dissolved during processing, leaving pale, empty-looking cells. This description is the hallmark of clear cell renal cell carcinoma, which is the most common type of kidney cancer. The clear cytoplasm isn’t just a visual quirk—it signals a specific cellular makeup with lipids and glycogen that gives the tumor its typical look and behavior.

Other kidney cancers have different cellular appearances. Papillary carcinoma tends to form finger-like projections (papillae) rather than clear cells. Oncocytoma shows cells with dense, eosinophilic granular cytoplasm due to many mitochondria, not clear cytoplasm. Chromophobe carcinoma has pale cytoplasm with distinct cell borders and characteristic raisinoid nuclei. So, the term that describes a kidney cancer where the cells appear clear under the microscope is the one that directly names the clear cytoplasm.