DNA Measurements in Lymphomatoid Papulosis: Evidence for this New Entity**From the Laboratory for Special Histochemistry, Veterans Administration Hospital, Allen Park, Michigan 48101, and the Departments of Dermatology and Pathology Wayne State University School of Medicine and Detroit General Hospital, Detroit, Michigan.

Lymphomatoid papulosis is a recently described type of pseudolymphoma cutis characterized by a benign course in spite of a lymphoma-like histology, in which numerous bizarre blast-like cells are present together with small, medium and large lymphocytes. The DNA content of nuclei in the infiltrate of lymphomatoid papulosis was measured in individual cells by Feulgen cytophotometry.1Small lymphocytes were comparable to those in other sites.2Medium and large lymphocytes displayed an aneuploid distribution of DNA, but there was little scatter from the secondary mode at 2x and there were neither intermediate forms nor hypertetraploid cells. These characteristics conform to those seen in a rapidly growing but non-malignant cell population.3DNA in the large blast cells was hypertetraploid in more than 40% of the cells. While this finding is usually associated with malignant growth, we found no cytophotometric evidence of cell renewal among these blast cells (no intermediate DNA values) and, taken with the benign clinical course and the frequent bizarre mitoses, an annihilatory mechanism seems likely. The suggestion is made that an intact immune mechanism plays some role