DNA image cytometry in malignant and benign sweat gland tumours

The histopathological differentiation between well‐differentiated carcinomas and atypical adenomas of sweat gland origin may be difficult, even if immunohistochemical methods are used. Therefore, additional techniques may be helpful. We previously demonstrated that DNA image cytometry (ICM‐DNA) can be useful in distinguishing between malignant and benign clear cell hidradenoma. In the present study, a larger series of sweat gland tumours, with a clear‐cut diagnosis as malignant or benign on histopathological criteria, was examined by ICM‐DNA. Enzymatic cell separation specimens were prepared from paraffin‐embedded tissues of 18 sweat gland carcinomas (14 porocarcinomas, one classic eccrine adenocarcinoma, two microcystic adnexal carcinomas and one mostly ductal apocrine carcinoma) and 47 benign sweat gland tumours (three syringocystadenomas, five spiradenomas, 14 cylindromas, three syringomas, seven nodular hidradenomas, 10 cutaneous mixed tumours, four poromas and one apocrine hidrocystoma). Specimens were examined by ICM‐DNA according to the current recommendations of the European Society for Analytical Cellular Pathology with the AutoCyte QUIC‐DNA workstation using mesenchymal cells as an internal reference. DNA aneuploidy was detected by the stemline interpretation according to Böcking and/or at least three 5[c]‐exceeding events. DNA aneuploidy was detected in 16 of 18 (89%) of the sweat gland carcinomas, but in none of the 47 adenomas. These results suggest that the detection of DNA aneuploidy in sweat gland tumours using ICM‐DNA is a clear and specific indicator of prospective malignancy.