Spindle Cell Lipoma with Ossification Mimicking Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma: A Case Report

Abstract

Although spindle cell lipoma (SCL) is a subtype of lipoma, the characteristics of SCL are observed in both lipomatous and non-lipomatous tumors. In this article, we present a case of SCL with ossification mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALTs/WDLs). Considering the findings of magnetic resonance imaging and needle biopsy, which exhibited ALTs/WDLs, marginal resection was performed. Histopathological findings demonstrated mature adipocytes and spindle cells without atypia and no malignant osteoid tissue in the ossified region. In addition, immunohistochemistry (IHC) showed positive staining for CD34, heterogeneous retinoblastoma protein deficiency, and negative staining for mouse double minute 2 homolog (MDM2) and cyclin-dependent kinase. Fluorescence in-situ hybridization showed negative amplification of MDM2. The final diagnosis of the tumor was established using IHC as an extremely rare SCL with ossification.

Case report: Atypical spindle cell/pleomorphic lipomatous tumor masquerading as a myxoid liposarcoma or intramuscular myxoma

“…The distinctive differences in clinical features between ASPLT and spindle cell lipoma (SCL) are sex and anatomic location (4,12). Approximately 60% of patients with ASPLT are men, and most are in their 50s.…”