A rare case of dedifferentiated liposarcoma of the thigh presenting as a vascular lesion with infective features.

Abstract

Background: Dedifferentiated liposarcoma (DDLPS) is a rare malignant soft tissue tumor which is the aggressive subtype of liposarcoma. Sometimes, they show some non specific clinical and radiological features. These atypical presentations may mimic benign or infectious conditions, which can create diagnostic challenges.

Case presentation: A 60 year old female presented with progressive swelling of the thigh associated with eneralized

weakness, prolonged intermittent fever, and weight loss. The swelling also increased gradually and later became tender with associated unilateral leg edema. Initial doppler ultrasonography revealed a vascular soft tissue tumor in the medial compartment of the thigh, suggestive of hemangioma. Subsequent contrast enhanced CT revealed mixed density with central necrosis suggestive of an organized abscess. MRI showed a large encapsulated mass involving surrounding thigh muscles. Due to diagnostic uncertainty, ultrasound guided aspiration was performed which revealed  purulent material and core biopsy was taken. However , histopathological examination revealed spindle shaped tumor cells with nuclear pleomorphism, atypical mitoses, lipomatous differentiation with lipoblast, and tumor necrosis, confirming dedifferentiated liposarcoma. Subsequent PET CT showed no distant metastasis.

Conclusion: This case highlights the diagnostic challenges of deep soft tissue tumors that may mimic benign or infectious conditions. Progressive enlargement of  a soft tissue mass with atypical imaging findings should raise suspicion for malignancy, and histopathological evaluation remains essential for definitive diagnosis.

Bangladesh J Medicine 2026; Vol. 37, No. 2(1): pp. 231