Aspiration biopsy in renal angiomyolipoma.

Ultrasound guided aspiration biopsy of renal mass lesions was performed in 56 patients in whom renal cell carcinoma could not be excluded due to equivocal imaging results. Cytology showed non-malignant mesenchymal cells consistent with angiomyolipoma in 12 patients. In 5 of these patients the diagnosis was ensured by open biopsy. No nephrectomy was performed. In 6 of the 7 patients not operated upon the tumours remained unchanged with no evidence of malignancy during a 3-36 months' follow-up period. Aspiration biopsy is an easy and safe method for diagnosing renal angiomyolipoma in cases where computed tomography is not diagnostic for this disease.