Leiomyomatous nodules and bundles of vascular origin in the fibrosarcomatous variant of dermatofibrosarcoma protuberans

Abstract

We report 5 cases of the fibrosarcomatous variant of dermatofibrosarcoma protuberans, 4 of which presented a morphologic change of intraneoplastic blood vessels not previously recognized. This change consisted of focal proliferation of smooth muscle cells, resulting in hypertrophy, generally eccentric, of vascular walls with reduction and collapsing of vascular lumina. In 3 cases the proliferation was so intense it formed leiomyomatous nodules and bundles. This proliferation may originate in the smooth muscle cells of the vessel walls either by means of a hyperplastic mechanism or in the pericytes via a line of differentiation leading to mature smooth muscle cells. In either case, we believe that it concerns a reactive process of the vessel walls very probably induced by adjacent neoplastic cells. The cases recently reported by Calonje and Fletcher as "myoid differentiation" of neoplastic cells in dermatofibrosarcoma protuberans (DFSP) may well be an expression of the same phenomenon, and therefore the presence of leiomyomatous areas in this tumor should not be used to support the theory of a fibroblastic/myofibroblastic line of differentiation for DFSP.

Dermatofibrosarcoma protuberans: A clinicopathological, immunohistochemical, genetic ( COL1A1-PDGFB ), and therapeutic study of low-grade versus high-grade (fibrosarcomatous) tumors

“…5,27,30 Although DFSP have infiltrative borders, the DFSP-FS in our series often exhibited an expansive pattern in some part of the tumor. These findings have been reported previously by Connelly and Evans 30 and Sanz-Trelles et al 31 We believe it is important to recognize this expansive feature associated to fibrosarcomatous zones, which can otherwise be CD34 e , to avoid misdiagnosis.…”

Dermatofibrosarcoma Protuberans of the Vulva With Myoid Differentiation

“…This is a very rare variant of DFSP, with less than 30 cases reported in the literature. [3][4][5][6][7][8][9][10][11] Table 1 summarizes the clinical and histopathologic characteristics of all cases of DFSP with myoid differentiation described to date, including our case. The majority of reports described the myoid variant appearing within areas of FS-DFSP.…”

“…2 We describe the case of a large DFSP, located on the vulvar area, which histopathologically showed areas of fibrosarcomatous and myoid differentiation. The myoid variant of DFSP is very uncommon, with less than 30 cases described in the literature so far, [3][4][5][6][7][8][9][10][11] and the nature of these myoid areas is still controversial.…”

Myxoid Dermatofibrosarcoma Protuberans of the vulva with myoid nodules: Clinicopathologic and Immunohistochemical study of a case

“…An unusual feature of DFSP is the myoid nodule. Originally construed as evidence of myofibroblastic differentiation [6], these structures seem to be centred in some cases around blood vessels [7,8], as seen in our case and likely represent an unusual non neoplastic vascular response to the tumor. Immunohistochemical findings are consistent with the typical DFSP, with the positive staining for CD34 ranging from 84% to 100%, and negative for other markers, such as S-100, desmin and actin [9].…”