Clear‐cell variant of superficial cutaneous leiomyosarcoma associated with RB1 mutation: Clinical, dermoscopic, and histopathological characteristics

Abstract

Leiomyosarcoma is a relatively rare soft tissue tumor whose clear-cell variant has only been reported in leiomyosarcomas of the uterus. We report here for the first time a primary cutaneous clear-cell leiomyosarcoma in the trunk skin of a 49-yearold man, characterized by a very indolent clinical and dermoscopic presentation, mimicking a dermatofibroma. Genetic analysis of the otherwise healthy patient revealed a germline mutation in the retinoblastoma 1 gene (RB1); the same mutation was found in his son, who had previously developed retinoblastoma. Moreover, the mother of the patient had died of uterine leiomyosarcoma with clear-cell changes. Mutations in the RB1 gene occur commonly in human neoplasms. In this patient, we were able to link his clear-cell variant of cutaneous leiomyosarcoma with the loss of retinoblastoma protein expression, as revealed by immunohistochemical staining analysis. K E Y W O R D S clear-cell leiomyosarcoma, dermoscopy, RB1 gene mutation, superficial cutaneous leiomyosarcoma

Clear Cell Leiomyosarcoma of the Anterior Abdomen -a Rare Case Presentation

“…It occurs commonly in abdomen, retroperitoneum, large blood vessels and the uterus [2]. Incidence of occurrence in extremities is less as compared to other soft tissue sarcomas [3]. Our patient presented with an anterior abdominal mass for the last one year.…”

“…Retroperitoneum is commonest site of involvement making 12-69.0% of the cases [2]. Uterus and skin are the only sites where clear cell variant of leiomyosarcoma has been reported [3].…”

Arborizing Telangiectasias May Also Be a Dermoscopic Vascular Pattern of Cutaneous Leiomyosarcoma

“…Two additional descriptions were presented as dermoscopic mimickers. 2,5 One case resembled a nonpigmented basal cell carcinoma, 5 whereas the second mimicked a dermatofibroma. 2…”

“…2,5 One case resembled a nonpigmented basal cell carcinoma, 5 whereas the second mimicked a dermatofibroma. 2…”

“…Furthermore, we visualized white structures and scar-like features, confirming previous descriptions. 1,2,5 Regarding vascular structures, Zaballos and colleagues 1 reported their presence in 8 of the 9 cases of cutaneous leiomyosarcomas. Most cases had a polymorphic vascular pattern and only one case had nonfocused arborizing telangiectasias.…”