Benign and malignant eccrine poroma--a flow cytometric comparison.

Eccrine poroma is a benign, slow growing, solitary adnexal tumor. Malignant degeneration may take place in longstanding solitary lesions; in such cases cutaneous and fatal visceral metastases have occurred. Our goal was to determine whether flow cytometry yields useful diagnostic and prognostic information on benign and malignant eccrine poroma. Flow cytometric analysis of the nuclear DNA ploidy pattern was performed on four samples of eccrine poroma and five samples of malignant eccrine poroma. All the histograms of the eccrine poromas were diploid. Two of five specimens (40%) of the eccrine porocarcinoma were aneuploid, and the other three (60%) were diploid. The diploid pattern represents another expression of the benignancy of eccrine poroma. Since abnormal DNA content is often correlated with tumor grade, the aneuploid DNA histogram of 40% of the patients with malignant eccrine poroma is not a surprising finding in this cytologically malignant neoplasm.