Three Cases of Nodular Fasciitis

Abstract

We report three cases of nodular fasciitis. Case 1 was a 53-year-old Japanese female. A subcutaneous nodule developed on the flexor site of the left forearm 7days earlier, and spontaneously disappeared after biopsy. Case 2 was a 29-year-old Japanese female. A subcutaneous nodule developed on the flexor site of the right forearm 10 days earlier, and spontaneously disappeared after biopsy. Case 3 was a 64-year-old Japanese female. A subcutaneous nodule developed on the flexor site of the left forearm without recurrence after enucleation. The onset time was unknown. All patients exhibited irregularly-shaped nodules with a fingerlike projection in which pleomorphic spindle cells proliferated from the septa to the lobules in the subcutaneous tissue. A vague storiform pattern was noted in myxoid stroma in case 1. An intertwining arrangement was observed in collagenous stroma in case 3. Osteoclast-like giant cells were scattered. Immunohistochemically, all patients were positive for α-smooth muscle actin, but negative for desmin and CD34. The proliferation indexes of Ki-67were 20%, 20%, and 2% in case 1,case 2, and case 3 respectively. Although the index in case 3 was lower than those in previous reports, it may have been because of the late lesion at the time of enucleation. The accumulation of further cases is required to assess the Ki-67proliferation index in nodular fasciitis. Skin Research, 20: 115-121, 2021