Flow cytometric study of nodular fasciitis, proliferative fasciitis, and proliferative myositis.

DNA ploidy was assessed retrospectively, using flow cytometry, in 13 nodular fasciitis (NF) lesions, three proliferative myositis (PM) lesions, one proliferative fasciitis lesion, and 12 other benign fibrous lesions (BFLs). All were diploid. In view of the large amounts of cellular debris, cell cycle analysis was possible in only seven NF lesions, three PM lesions, and six BFLs. The mean percentage of S phase did not differ markedly between the combination of NF and PM lesions (6.6%) and BFLs (7.1%); the mean percentage of G2 + M phase (5.4%) of the NF/PM lesion combination was twice as large as that of the BFLs (2.5%). No correlation was detected between the cell cycle analysis and the mitotic count, the predominant histologic type in NF lesions, or the predominant stroma in PM lesions.