Other unusual manifestations include liver function abnormalities and the development of high-output congestive heart failure, presumably secondary to the formation of arteriovenous fistulas. In the past, renal carcinomas were classified on the basis of cell type and growth pattern. This classification has undergone a transformation that more accurately reflects the morphological, histochemical, and molecular aspects of differing types of adenocarcinomas. Five distinct carcinoma types have been identified. Each of these carcinoma types has a unique growth pattern, cell of origin, and cytogenetic characteristics.
Renal ultrasonography helps distinguish simple cysts from more complex abnormalities.
A simple cyst is defined sonographically by a lack of internal echoes, by the presence of smooth borders, and by transmission of the ultrasound wave. If all three features are present, the cyst is most likely benign. Although cyst puncture was once routinely used for diagnosing renal cystic lesions, this procedure is not necessary for asymptomatic patients without hematuria. Periodic repetition of the ultrasound examination is suggested for such patients. If any change in the lesion occurs, cyst puncture, needle aspiration, or further study by abdominal CT scanning should be considered.