[Some considerations on clear cell tumors, especially in the lungs (author's transl)].

On the basis of 4 cases seen by the author and comparative reports in the literature the following observations were made: 1. Clear cell tumors of the lungs must be considered as semimalignant (or malignana). 2. Malignant degeneration may be associated with a loss of the clear cell character. 3. Clear cell areas are not infrequently seen in common pulmonary carcinomas. 4. Histological differentiation between primary clear cell tumors and metastases (e.g., metastatic hypernephroma) may not be possible. In addition, some general observations on extrapulmonary clear cell tumors will be discussed.