Dedifferentiated Leiomyosarcoma of the Uterus with Heterologous Elements: A Potential Diagnostic Pitfall

Abstract

Dedifferentiation is a phenomenon that is well characterized in a variety of tumors and is defined by the occurrence of a high-grade or undifferentiated tumor, typically unrecognizable regarding its line of differentiation, from a low-grade/borderline neoplasm. This phenomenon has previously been described in 2 uterine leiomyosarcomas, but both were devoid of heterologous elements. The authors describe herein a case of a dedifferentiated leiomyosarcoma of the uterus with osteoid heterologous elements, believed to be the first such reported case. The original tumor was a high-grade leiomyosarcoma with large low-grade and leiomyoma-like areas and whose constituent cells displayed intense nuclear immunoreactivity for both estrogen receptor (ER) and progesterone receptor (PR) in approximately 30% of cells. The tumor recurred six months after its resection as an undifferentiated sarcoma that was negative for smooth muscle markers, but which remained positive for ER and PR. Osteoid production was only identified in the recurrent tumor and was significant in extent therein. This case highlights the immunophenotypic changes that may occur in dedifferentiated leiomyosarcomas, and this possibility should be a consideration when an apparently undifferentiated sarcoma is identified in a patient with a history of uterine leiomyosarcoma. In our case, the expression of ER and PR provided significant supportive evidence of the uterine origin of the recurrent tumor.

Dedifferentiated leiomyosarcoma of the uterus: a clinicopathologic and immunohistochemical analysis of 23 cases

“…Review of the literature identified 11 primary dedifferentiated uterine LMS. 12,[16][17][18][19][20][21] Follow-up was available in six cases, of whom three had died of disease at 4, 6, and 17 months, 16,17 one had died of other causes at 12 months, 12 and two were alive without disease at 12 and 28 months. 12,19 The literature also contains eight additional cases of primary conventional uterine LMS with subsequent dedifferentiation at metastatic sites, 16,21 with death from disease at median 7 months (range 1-18 months) after dedifferentiation.…”

“Malignant Mesenchymoma” Revisited

“…A comprehensive literature review including LMS and the terms "malignant mesenchymoma," "pleomorphic," "heterologous," "osteosarcoma," and "osteoblastic" yielded 12 cases of LMS with OS. 16,[18][19][20][21][22][23][24][25][26][27] The largest previously published study by Parikh et al 23 reported 2 cases of uterine LMS displaying heterologous OS. The prevalence of LMS with OS in our study out of all LMS cases was 0.2%.…”

“…Heterologous OS is well recognized in sarcomas of soft tissue and bone (eg, dedifferentiated liposarcoma, dedifferentiated chondrosarcoma, and malignant peripheral nerve sheath tumor); other tumor types that rarely show OS include pleural mesothelioma, malignant phyllodes tumor, and mullerian adenosarcoma, among others;17 however, this phenomenon has only rarely been reported in LMS, as individual case reports. A comprehensive literature review including LMS and the terms “malignant mesenchymoma,” “pleomorphic,” “heterologous,” “osteosarcoma,” and “osteoblastic” yielded 12 cases of LMS with OS 16,18–27. The largest previously published study by Parikh et al23 reported 2 cases of uterine LMS displaying heterologous OS.…”

High grade sarcoma with chondrosarcomatous differentiation in primary uterine leiomyosarcoma; A rare case and review of literature

“…The primary tumor showed morphology consistent with high-grade LMS. The patient presented with the recurrent disease six months later and histomorphological examination revealed undifferentiated sarcoma with osteoid formation ( Rawish and Fadare, 2012 ). Chen et al ( 2011 ) investigated 18 cases of de-differentiated LMS from various sites including two uterine cases.…”