Table 1 Differential diagnosis of eosinophilic renal cell carcinoma and associated characteristic features

Renal Oncocytoma

Classically mahogany brown, well-circumscribed lesion with a central scar

Small solid nests of cells within myxoid or hyalinized stroma. Densely eosinophilic cytoplasm. Nuclei are uniform and round. Prominent nucleoli, typically lacking binucleanation.

Cytokeratin 7: isolated scattered cell staining.

Chromophobe RCC

Usually solitary well-circumscribed grey-beige colored lesion

Solid growth pattern with thin fibrovascular septa. Abundant cytoplasm with prominent cell borders. Nuclei with preserved chromatin and irregular, winkled nuclear membrane.

Cytokeratin 7; usually diffuse staining

Clear cell RCC, eosinophilic variant

Generally golden/yellow color with extensive hemorrhage and necrosis.

Clear cells, although the cytoplasm may be eosinophilic in higher grade tumours. Nested growth pattern. Rich sinusoidal vasculature, often called “chicken wire-like” vasculature.

Positive for CD10, CA-9, EMA, vimentin, and RCC antigen.

Negative for CK7 and high-molecular weight keratin.

SDHB signal may be weak due to the abundant clear cytoplasm.

TF3 translocation RCC

Yellow-tan with areas of hemorrhage and necrosis

Papillary architecture lined by clear and eosinophilic cells with abundant psammoma bodies. Clear to pale pink fluffy cytoplasm.

Positive for TFE3

SDH-deficient RCC

Tan to red well-circumscribed solid lesions with cystic changes common.

Eosinophilic cells with clear (flocculent) cytoplasmic inclusions, round nuclei with mildly granular chromatin pattern, and solid architecture.

Loss of SDHB is a diagnostic requirement

Positive for PAX8 and EMA

Negative for CK7, CK20, AE1/AE3, and CD117

Other: