A DNA-flow cytometric analysis of trichilemmal carcinoma, proliferating trichilemmal cyst and trichilemmal cyst.

DNA-flow cytometric analyses were performed on paraffin-embedded sections of trichilemmal carcinoma, proliferating trichilemmal cyst, and trichilemmal cyst. Nine out of 10 cases of trichilemmal carcinoma and 2 out of 5 cases of proliferating trichilemmal cyst showed aneuploidy. No aneuploidy was detected in 6 cases of benign trichilemmal cyst. The proliferating index (percentage of cells that exceeded the diploid peak (G0/G1) plus 4 standard deviations) of trichilemmal carcinoma, proliferating trichilemmal cyst, and trichilemmal cysts was 43.5 +/- 3.8%, 32.5 +/- 7.5%, and 23.1 +/- 2.0%, respectively. In one out of the 6 cases of trichilemmal carcinoma that were large enough for us to investigate regional differences, DNA ploidy heterogeneity was detected. The incidence of aneuploidy of trichilemmal carcinoma was significantly higher than that of squamous cell carcinoma (14%), previously described by us using the same method.