Deoxyribonucleic acid flow cytometry of testicular Leydig cell tumors.

We analyzed by flow cytometry the deoxyribonucleic acid content of 13 paraffin embedded, formalin-fixed Leydig cell tumors of the testis. Of the tumors 10 were clinically benign (9 diploid and 1 aneuploid) and 3 were malignant (aneuploid). The benign aneuploid tumor showed moderate cellular atypia and a low mitotic count (less than 2 per 10 high power fields). Our study suggests that the majority of Leydig cell tumors are diploid and the less common malignant tumors are typically aneuploid, and that deoxyribonucleic acid flow cytometric findings can be useful as a prognostic indicator in these tumors.