Metastatic renal cell carcinoma of spleen diagnosed by fine-needle aspiration.

Splenic metastases are infrequent, and determination of the primary site by fine-needle aspiration (FNA) can be complex. We report the case of a 65-year-old man who was found to have a large heterogeneously enhancing 8 x 7-inch splenic mass by abdominal computed tomography (CT). FNA by transesophageal endoscopic ultrasonography demonstrated atypical cells conclusive for malignancy and consistent with metastatic renal cell carcinoma based on cytomorphology, histochemical lipid positivity, and immunohistochemical positivity for cytokeratin, vimentin, and renal cell carcinoma marker. Repeat CT with and without arteriovenous contrast demonstrated bilateral renal cysts, including a 0.9 x 0.8-cm lesion on the left with significant enhancement. Splenectomy confirmed the radiological and cytological findings, and left kidney exploration and nephrectomy demonstrated a small (1.5 cm) lower pole renal cell carcinoma of chromophil (papillary) type, histologically similar to the splenic metastasis. This case demonstrates the diagnostic importance of interdisciplinary involvement (oncology, radiology, gastroenterology, pathology, and general and urologic surgery); cytomorphology; histochemistry, including fat stain on frozen cell block; and immunohistochemistry, including the recently developed renal cell carcinoma marker.