Primary cutaneous leiomyosarcoma. A histological and immunohistochemical study of 9 cases, with ultrastructural correlation

Abstract

Leiomyosarcoma (LMS) of dermal and subcutaneous tissues is an uncommon neoplasm. In order to analyze the specialized pathologic features of this tumor, we undertook a histological, ultrastructural, and immunohistochemical study of 9 superficial LMS, including 7 dermal lesions and 2 subcutaneous neoplasms. These were compared with 12 examples of "deep" extracutaneous LMS. Metastases to the skin from two of the latter neoplasms were also examined. Immunohistochemistry was found to be a useful diagnostic adjunct to light microscopic and ultrastructural studies in that all LMS coexpressed vimentin and desmin, regardless of site, and 90% also expressed muscle-specific actin. Variable expression of cathepsin B and myelin basic protein was noted in 8 and 10 tumors, respectively, whereas none contained cytokeratin. Weak cytoplasmic positivity for epithelial membrane antigen was seen in 1 dermal and 3 extracutaneous LMS. Of 7 dermal LMS, 4 contained S-100 protein, whereas this determinant was found in only 1 of 12 extracutaneous tumors. Conversely, Leu 7 reactivity was present in 7 of 12 extracutaneous LMS, but only 2 of 9 superficial lesions. Review of clinical features confirmed that subcutaneous LMS is capable of aggressive behaviour, whereas dermal LMS was more likely to behave in an indolent fashion. However, one example of dermal LMS exhibited aggressive local recurrences and distant metastasis, ultimately leading to the death of the patient. Therefore, careful clinical followup is indicated in all cases.

Solitary Dermal Leiomyosarcomas in 12 Ferrets

“…This case suggests that definitive identification of some dermal leiomyosarcomas in the ferret may not be possible by immunohistochemistry, and electron microscopic evaluation may be needed to establish a definitive diagnosis. 12 In this limited study, dermal leiomyosarcomas occurred more often in male than in female ferrets. In humans, females are affected more often than males, with a sex ratio of 1.7 11 to 3.7.…”

“…In contrast, poorly differentiated dermal leiomyosarcomas may be difficult to differentiate from other spindle-cell sarcomas, including fibrosarcomas and malignant peripheral nerve sheath tumors. In humans, immunohistochemical evaluation aids in establishing a definitive diagnosis in most cases because most dermal leiomyosarcomas are positive for desmin and smooth muscle actin, 7,12,15 whereas other dermal and subcutaneous sarcomas are negative. Of the tumors reported here, 1 well-differentiated dermal leiomyosarcoma was negative for these antigens.…”

Transgelin is a novel marker of smooth muscle differentiation that improves diagnostic accuracy of leiomyosarcomas: a comparative immunohistochemical reappraisal of myogenic markers in 900 soft tissue tumors

“…6 Desmin appears to be the least sensitive of all markers in this study, although its expression in leiomyosarcomas has been shown to be extremely variable in published series, ranging from 50 to almost 100% positivity. 7,18,19,20 More particularly, this study showed that transgelin is the most sensitive marker in leiomyosarcomas, emerging as a basic immunostain useful in the diagnosis of leiomyosarcomas, especially in those cases with incomplete immunophenotypes potentially not displaying labeling with actin, desmin, calponin or h-caldesmon. When smooth muscle actin is negative, calponin, desmin and h-caldesmon are also more likely to be negative, except for in GIST and rare cases of the so-called 'inflammatory leiomyosarcomas'.…”

Clinical course of nonvisceral soft tissue leiomyosarcoma in 225 patients from the Scandinavian Sarcoma Group

“…Only a few LMS studies 4,[8][9][10][11][12][13] of any significant size included clinical and follow-up data, and several others [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] analyzed limited numbers of patients with primary LMS at these sites. In addition, many of the previous studies are difficult to interpret, because heterogeneous tumor groups were studied without specifying the localization relative to skin or fascia or the anatomic site.…”