[Incidence and differential diagnosis of hyperechoic kidney tumors].

The frequency of kidney tumours was determined in a prospective study of 11,076 consecutive patients investigated sonographically in a department of internal medicine. A further objective of the study was to establish whether the echo characteristics of the renal tumours alone allow sonographic categorization into benign and malignant tumours, how often it is possible to diagnose angiomyolipomas of the kidneys on the basis of sonography alone, and how frequently further imaging techniques and/or invasive methods are necessary. In this patient series, 68 solid renal lesions were detected (0.6%): 15 of the lesions were hypernephroid carcinomas (0.13%) and 28 angiomyolipomas (0.25%). All angiomyolipomas were hyperechoic. In contrast, only 3 of the hyperechoic tumours were hypernephroid carcinomas. Owing to the unequivocal sonographic appearance, 16 out of 28 angiomyolipomas could be diagnosed on the basis of sonography alone. Additional diagnostic measures were necessary for only 12 of these tumours (CT, angiography, intravenous pyelogram, and an operation in 1 patient, who had an angiomyolipoma infiltrating into the vena cava). In contrast to this, computer tomography was necessary in addition for the diagnosis of all malignant tumours, and angiography in 4 cases.