Incidence of mature adipocytic component within cutaneous smooth muscle neoplasms

Abstract

Angioleiomyoma is a benign smooth muscle tumor of the subcutis. The presence of mature adipocytes has been described in this tumor under the rubric of 'angiolipoleiomyoma' or, erroneously, 'angiomyolipoma' (these are not PEComas). Previous studies have found adipocytes in only 2-3% of angioleiomyoma. Anecdotally, the incidence appeared to be greater than this in our practice. Moreover, the presence of adipocytes has not been evaluated in pilar leiomyoma or cutaneous leiomyosarcoma. We searched the pathology archives from 2007 to 2014 for all cutaneous and subcutaneous leiomyoma and leiomyosarcoma; cases were reviewed to confirm the diagnosis and evaluate for mature adipocytes. Seven of 73 total cases (10%) contained mature adipocytes: 1 of 33 pilar leiomyoma (3%), 4 of 22 angioleiomyoma (18%) and 2 of 18 leiomyosarcoma (11%). In our series, the 18% incidence of 'angioleiomyoma with fat' (our preferred terminology) is higher than the previously reported incidence of 2-3%. We also report the rare presence of mature adipocytes within pilar leiomyoma and cutaneous leiomyosarcoma, a finding not previously reported to our knowledge. Mature adipocytes may be present within cutaneous and subcutaneous leiomyomas and leiomyosarcomas and should not detract from the diagnosis or lead to concern for an adipocytic neoplasm or PEComa.

Inhibition of WNT/β-catenin signaling under serum starvation and hypoxia induces adipocytic transdifferentiation in human leiomyoma cells

“…The proportion of the fatty component within the lesion is highly variable and may be shown as an almost entirely fatty neoplasm simulating lipoma. Several pathogenetic mechanisms underlying the presence of fat cells within leiomyoma have been discussed previously [3][4][5]16]. Although the direct transformation (metaplasia or Our study demonstrated that adipocytic transdifferentiation, as shown by intracellular lipid accumulation and the enhanced expression of adipogenic markers (i.e., adiponectin, perilipin-1), can be elicited in cultured uterine leiomyoma cells by XAV939 treatment together with serum starvation and hypoxia.…”

“…Adipocytic transdifferentiation or metaplasia may be representative forms of such phenotypic plasticity. The phenomenon is most commonly encountered in neoplastic conditions of smooth muscle cells such as leiomyomas and angiomyomas [1][2][3]. However, the detailed mechanisms underlying adipocytic transdifferentiation remain largely unknown; however, the adipocytic differentiation of pluripotent mesenchymal cells in such lesions and the direct transformation of neoplastic smooth muscle cells are possible explanations [3][4][5].…”