[Calcification in mass lesions in the kidney (author's transl)].

In 80 mass lesions of the kidney, we found 11 cases with calcification; six of these occurred amongst 48 tumours and five amongst 32 solitary cysts. In particular, the following were found: 1. The frequency of calcification of 12 to 14% corresponds with that given in the literature. If other radiological signs fail indicate the nature of the space-occupying lesion, then calcification may be of diagnostic value. 2. Calcified cyst walls appear as fine, even, curvi-linear lines, Dense, irregular and extensive calcification indicates a solid tumour. 3. Ring or curvi-linear calcification in not a reliable sign of a cyst. Tumours may also show this type of calcification indicates a solid tumour. 3. Ring or curvi-linear calcification is not a reliable sign of cyst. Tumours may also show this type of calcification. Calcification occurs in solitary cyst with about the same frequency as in tumours. 4. Histologically all calcified tumours were clear cell carcinomas, mostly hypervascular. Only one case showed central necrosis.