The ultrasonic spectrum of benign and malignant renal "cystic" masses--differential diagnosis and diagnostic difficulties.

This paper discusses the differential diagnosis of renal cystic masses with non-grey scale ultra-sound scanners, and presents some limitations of the equipment. Included among cystic masses are serous cysts, hemorrhagic cysts, calcified cysts, hydronephrosis, abscesses, and necrotic tumors. Technical aspects of scanning of very important. Only single sweep scans are performed, usually as a series of closely spaced scans during suspended respiration. Breathing during scanning, and compound scanning, degrade image sharpness and can completely obscure small cysts. Serous cysts and hydronephrosis usually present distinct and different ultrasonic appearances. Necrotic tumors, hemorrhagic cysts, and abscesses can not be differentiated. Cysts with calcified walls can not be identified as cystic masses because the calcium within the wall prevents sound from penetrating through the mass. To confirm the diagnosis of a renal cystic mass, percutaneous puncture under ultrasonic guidance can be performed. Fluid is removed for laboratory studies and radio-opaque contrast material is instilled within the cavity. X-rays are then to better define the contours and internal architecture.