Possible case of dermatomyofibroma exhibiting paradoxical reduction of elastic fibers

Abstract

Dear Editor, Dermatomyofibroma (DMF) is a relatively rare fibrous tissue benign tumor that was first described by Hugel in 1991 under the name of plaquelike dermal fibromatosis.1 Kamino et al.2 in 1992 proposed use of the name DMF for the tumor, which is a proliferation of fibroblasts and myofibroblasts of the skin. Although predominant in young female patients in their 20s to 30s, male patients tend to be much younger than their female counterparts.2 The tumor is commonly located on the shoulder and neck, and is a welldefined round or oval shape, with it sometimes exhibiting a cordlike plaque or nodules. The patient generally has no symptoms or histories of trauma.2 It is often misdiagnosed as other diseases or conditions3 and their histological differentiations are summarized in Table S1. A 60yearold man presented with a cordlike tumor near the cranial side of the right anterior thoracic areola. Although the lesion had been initially noticed approximately 10 years earlier, it recently started to enlarge. The brownish red tumor was 35 mm × 7 mm and exhibited no tenderness (Figure 1a). The patient had no history of trauma associated with the lesion. The tumor was composed of spindleshaped cells arranged in a densely cellular fascicle that ran roughly parallel to the epidermis in the middle or deep portion of the dermis (Figure 1b). Elongated nuclei without atypia were observed in each of the tumor cells (Figure 1c). The tumor cells were positive for αsmooth muscle actin and vimentin, and negative for CD34, factor 13a, and S100 (Figure 1d, Figure S1). These physiological and histopathological findings in the present case are consistent with those of DMF, although the elastic fibers were conspicuously reduced and fragmented (Figure 1e,f). An increase in the amount of elastic fibers has been reported to be one of the pathological features of DMF and might reflect the function of the myofibroblasts, which are known to produce more elastic fibers as compared to fibroblasts.4 Contrary to these findings, elastic fibers in the tumor in the present case were conspicuously reduced, as compared to that observed in the surrounding tissues. Aging alone cannot sufficiently explain the reason for our observed lesionspecific reduction in the elastic fibers. In fact, increases in elastic fibers have also reported in the case of a 52yearold male.5 As shown in Table S1, fibroblastic connective tissue nevus, which is characterized by myofibroblast proliferation and decreased elastic fibers, can be clearly ruled out in the present case. The peculiar reduction of elastic fibers in the present case could indicate impaired function of the myofibroblasts within the lesion. This type