Multilocular renal cyst: A diagnostic pitfall on fine‐needle aspiration cytology: Case report

Benign renal lesions, apart from simple cysts, are rarely sampled by fine‐needle aspiration biopsy (FNAB) and are potential diagnostic pitfalls. A complex renal mass in a 33‐yr‐old pregnant woman, presenting in the second trimester with haematuria, was aspirated twice, a week apart, under ultrasound guidance. The second FNAB yielded predominantly mesenchymal elements thought to represent an angiomyolipoma, but the mass was identified as a multilocular renal cyst (MLRC) on the nephrectomy specimen. Differential diagnoses of angiomyolipoma, MLRC, and renal cell carcinoma (RCC) are compared and discussed in relation to patient management. © 1995 Wiley‐Liss, Inc.