Multiparameter DNA flow cytometry of keratoacanthoma.

Keratoacanthomas (KAs) are rapidly growing cutaneous lesions that frequently look much like well-differentiated squamous cell carcinomas (SCCs) but spontaneously regress. It is uncertain whether KA is a reactive hyperplastic lesion that mimics a neoplasm or a true (but defective) neoplasm that cannot sustain progressive growth. To address this question, we performed DNA flow cytometric analysis on 14 KAs and 10 cutaneous SCCs for comparison. By multiparameter DNA flow cytometry using forward scatter and orthogonal scatter, 10 KAs and 4 SCCs had peridiploid DNA aneuploid populations (DNA indices of 1.03-1.14), and 2 SCCs had grossly aneuploid populations (DNA index, 1.69 and 2.33). Our data thus support aneuploidy in KAs. It is argued that KA is a true neoplasm.