Metastatic clear cell renal carcinoma to the auricular region disguised as a vascular thrombus: Case report.

In about 25-30% of patients with primary renal cell carcinoma, metastasis is not uncommon and usually does not give rise to difficulties in diagnosis. However, its presentation as a subcutaneous mass following an elapse of several years after the initial diagnosis is not only uncommon but may be also mistaken for a thrombus in imaging studies due to its common high vascularization. We present here a case of a 70-year-old woman with an oncologic history of renal cell carcinoma who noticed after five years a mass in the auricular region radiologically suggestive of a vascular thrombus. Fine-needle aspiration cytology showed malignant epithelial cells compatible with metastasis of renal clear cell carcinoma, supported by immunohistochemistry performed on the cell block. This rather uncommon presentation and precise diagnosis by fine-needle aspiration prompted us to report the case, emphasizing the role of cytopathology as a useful, fast and minimally invasive method for clarifying the neoplastic nature of highly vascularized lesions.