Xp11 Translocation Renal Cell Carcinoma Morphologically Mimicking Clear Cell–Papillary Renal Cell Carcinoma in an Adult Patient

Xp11 translocation renal cell carcinoma (RCC) is a relatively rare tumor mainly affecting children and adolescents. It shows significant morphological overlap with the 2 most common adult renal tumors, which are the clear cell (conventional) RCC and papillary RCC. We describe case of a young adult female who presented with right flank pain and abdominal mass. Radiological investigations showed features suggestive of renal cell carcinoma in the right kidney. Histopathological findings while suggestive of Xp11 carcinoma, showed significant overlap with the recently described entity clear cell papillary RCC. TFE3 immunohistochemistry confirmed the tumor to be Xp11 translocation RCC. The patient had an aggressive course with lymph node metastasis. In this report, we discuss differential diagnosis and the diagnostic challenges of Xp11 translocation RCC in adults.