Leiomyosarcoma of the kidney. Report of a case diagnosed by fine needle aspiration cytology and electron microscopy.

A 41-year-old man presented with a large abdominal tumor that yielded, in the fine needle aspiration biopsy, dyshesive, pleomorphic malignant cells. Electron microscopy of the aspirated material revealed nonepithelial cells showing intracytoplasmic bundles of microfilaments with vague focal densities and micropinocytotic vesicles along the cell membrane, suggesting a malignant leiomyosarcoma, which was confirmed by microscopic examination of the resected right kidney. The patient died four months after surgery from widespread metastases.