Unclassified Oncocytic Renal Neoplasm with Rib and Liver Metastases: Metastatic Oncocytoma?

Renal tumors with oncocytic or chromophobe-like morphology can be a common source of diagnostic difficulty. In some series, they constitute the largest group of unclassified renal cell carcinomas, a term used for neoplasms that do not fit the current classification of renal tumors. We describe the histological, immunohistochemical, and molecular findings of an eosinophilic renal neoplasm which presented with rib and liver metastases, and provide a review of the literature. The possibility of a renal oncocytoma with metastases was initially considered but excluded on the basis of several morphological and immunohistochemical features. Additionally, the tumor did not correspond with other traditional or newly emerging categories of renal neoplasms. It was therefore regarded as an unclassified oncocytic renal neoplasm which demonstrated evidence of malignant potential due to the presence of multiple metastases.

Asymptomatic renal cell carcinoma with metastasis to the skin and duodenum: a case report and review of the literature.

Renal cell carcinoma is known to have blood-borne metastasis. This is usually to the bone, lungs and brain. Other unusual metastatic presentations such as skin and bowel metastasis have also been described. In most cases, the metastasis occurs as a late manifestation in a patient with known primary renal cell carcinoma. A rare synchronous presentation of skin and duodenal metastasis in an otherwise asymptomatic patient is reported here. This patient presented with a skin lesion that, on excision, brought up the diagnosis of metastatic renal cell carcinoma. While the patient was waiting for surgery, she also developed melena that, on gastroscopy, confirmed a duodenal metastasis. This case highlights the importance of early recognition of otherwise unrelated lesions as presentations for an advanced renal malignancy.