A primary leiomyosarcoma of bone containing pseudoepithelial plexiform elements

Abstract

A rare but distinctive variant of smooth muscle tumours that occurs almost exclusively in the uterus is characterised by the presence of plexiform tumourlets, which are composed of clumps and cords of tumour cells that form a discrete pseudoepithelial component. We report on a case of a primary leiomyosarcoma of the proximal humerus, which, in addition to characteristic histological and immunophenotypic features of leiomyosarcoma, contained plexiform tumourlets. Tumour cells in the plexiform component focally expressed muscle/smooth muscle actin, calponin and cytokeratin. Spindle-shaped and epithelioid smooth muscle tumour cells also expressed the above antigens. This is the first report of a plexiform smooth muscle tumour arising in bone. This case is remarkable, not only for being only the second reported case of a malignant plexiform smooth muscle tumour, but also for being one of very few examples of this type of tumour arising outside the uterus; it also is unique in having arisen in a male patient. This variant of primary leiomyosarcoma needs to be distinguished from other bone tumours containing epithelial elements, notably metastatic carcinoma.

Primary Leiomyosarcoma of Bone: Clinicopathologic and Prognostic Factors Analysis in a Single Institution

“…The most common affected organ is the lung. 2 , 15 Not in accordance to the findings in literature, our rate of DM was 40.9%, again, a considerable higher percentage. Nevertheless, and in accordance with the publications, we also have the lung as the predominant affected organ for DM.…”

“… 6 , 14 Most of the pathological reports for PLB are high grade tumors (FNCLCC). 2 , 8 , 15 In a series of three different studies, we found that high grade PLB was predominant. 7 , 12 , 14 In our study, high grade tumors were also predominant, but with 90.9%, which is a much higher percentage when compared to the reported in other studies.…”

Case report and literature review: Primary leiomyosarcoma of the bone in the trochanteric region of the femur

“…They are thought to originate from small vascular smooth muscle cells in the bone cortex or pluripotent mesenchymal stem cells in the bone. They are pathologically characterized as osteosarcomas with smooth muscle-like differentiation ( 3 ). Leiomyosarcoma commonly occurs in the retroperitoneum, subcutaneous tissue of the extremities, intraabdominal space, and gastrointestinal, uterine, and other deep soft tissues ( 4 ).…”