Study highlights challenges in identifying epithelioid dedifferentiated liposarcoma

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For patients with advanced stages of epithelioid dedifferentiated liposarcoma, treatment with CDK4 inhibitors may offer a targeted therapeutic option, potentially improving outcomes for this unique tumor type, according to a study that sheds light on this diseases clinical and pathological features, emphasizing its aggressive nature and potential challenges in diagnosis due to its distinctive appearance.

The research examined 6 cases of adult males, with a median age of 58.5 years. Initial symptoms were nonspecific, typically manifesting as retroperitoneal mass, intermittent dull pain, or discomfort. None of the patients had a prior history of a primary tumor.

Radiological examinations unveiled ill-defined, heterogeneous masses situated in deep soft tissue. Four cases were located in the retroperitoneum, while one each occurred in the pelvis and trunk. The tumors appeared as solid formations, with 2 cases exhibiting focal areas of necrosis.

Microscopic analysis revealed a distinctive pattern: all tumors were characterized by sheets of epithelioid cells exhibiting marked cellular atypia and vigorous mitotic activity. In 3 cases, a variable portion of atypical lipomatous tumor/well-differentiated liposarcoma was observed.

Immunohistochemistry found the high-grade epithelioid component consistently exhibiting strong and diffuse nuclear staining of MDM2, CDK4, and P16. Additionally, partial expression of AE1/AE3 was detected in 3 cases. Fluorescence in situ hybridization analysis confirmed high-level amplification of MDM2 in all cases, with co-amplification of CDK4 in 3 cases.

Two individuals died within 1 year, despite receiving multidisciplinary treatment.

Tu Y, Zhu P, Lao IW, et al. Epithelioid dedifferentiated liposarcoma: A clinicopathological and molecular study of 6 cases. Ann Diagn Pathol. 2023;67:152203. doi: 10.1016/j.anndiagpath.2023.152203. Epub ahead of print. PMID: 37634346.