A young female case of primary renal carcinoid tumor mimicking fat-poor angiomyolipoma.

Renal mass biopsy is useful for the pathological diagnosis of a small renal mass difficult to distinguish fat-poor angiomyolipoma from renal cell carcinoma radiologically. Here, we report a young female case of a small renal mass suspected as fat-poor angiomyolipoma in imaging studies. The patient received a renal mass biopsy to obtain the correct pathological information. Unexpectedly, the pathological diagnosis was neuroendocrine tumor. She, finally, underwent a right radical nephrectomy as a curative treatment. This case indicates that the radiological findings of primary renal carcinoid tumor can be similar to those of fat-poor angiomyolipoma.