Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Myxoid liposarcoma is a rare type of soft tissue sarcoma that typically arises as a deep-seated mass in the lower extremities of adults. However, its presentation as a primary subcutaneous tumor is uncommon. In this case, we describe an unusual clinical presentation of superficially located myxoid liposarcoma and highlight its differential diagnosis.

A 56-year-old male with a medical history of alcohol-associated pancreatitis, portal vein stenosis, and malnutrition presented with a lesion in his left lower extremity. Imaging revealed a relatively well-circumscribed, non-specific soft tissue mass (6.8x6.3x4.3cm) within the subcutaneous tissues of the medial proximal thigh. Fine needle aspiration smear and cell block analysis showed solid clusters of atypical lipoblasts, along with scattered single tumor cells. These clusters were moderately cellular and surrounded by amorphous material. Histologic examination revealed a hypocellular lesion composed of bland round to stellate cells evenly dispersed in a myxoid stroma. Delicate arborizing vasculature was also observed. A round cell component was present in the tumor, accounting for less than 5% of the overall tumor volume. Fluorescence in situ hybridization studies confirmed a DDIT3 gene rearrangement, supporting the diagnosis of myxoid liposarcoma.

Myxoid liposarcoma can mimic other more common dermal and subcutaneous tumors with prominent myxoid stroma. The characteristic microscopic features and demonstration of DDIT3 rearrangement are crucial for accurate diagnosis and differentiation from potential mimics. This case underscores the importance of recognizing atypical presentations of myxoid liposarcoma and highlights the need for thorough evaluation to guide appropriate management.

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Mohamed Hussein, M.D.