Can MDM2 analytical tests performed on core needle biopsy be relied upon to diagnose well-differentiated liposarcoma?

Well-differentiated liposarcoma/atypical lipomatous tumor can be difficult to differentiate from benign lipomatous tumors, especially on limited biopsy material. Adjunctive tests for MDM2 (murine double minute 2) have proven useful in whole-tissue sections; however, their utility has not been determined within the increasingly popular core needle biopsy. Herein, we compare the ability of MDM2 immunohistochemistry and MDM2 fluorescence in situ hybridization (FISH) to discriminate benign lipomatous tumors from well-differentiated liposarcoma on core needle biopsies.

Utility of FISH in the diagnosis of angiomatoid fibrous histiocytoma: a series of 18 cases.

Angiomatoid fibrous histiocytoma is a mesenchymal neoplasm of intermediate malignancy and uncertain histogenesis/line of differentiation, which occurs most commonly in the extremities of children to young adults. It has a characteristic appearance characterized by a proliferation of histiocytoid cells with a lymphoid cuff and fibrous pseudocapsule, simulating the appearance of a neoplasm occurring within a lymph node. However, these classic histological features are not always present.

Detection of MDM2 gene amplification or protein expression distinguishes sclerosing mesenteritis and retroperitoneal fibrosis from inflammatory well-differentiated liposarcoma.

Inflammatory liposarcoma is a variant of well-differentiated liposarcoma/atypical lipomatous tumor that consists of a mixture of lymphocytes, histiocytes, scattered atypical stromal cells, mature adipocytes, and rarely lipoblasts. When the inflammatory infiltrate predominates, the morphological features overlap with various fibroinflammatory disorders including sclerosing mesenteritis and retroperitoneal fibrosis, making the diagnosis difficult. Well-differentiated liposarcoma/atypical lipomatous tumor and dedifferentiated liposarcoma have characteristic molecular markers in the form of giant marker and ring chromosomes consisting of amplicons of 12q13-15, which includes MDM2.

Fluorescence in situ hybridization for MDM2 gene amplification as a diagnostic tool in lipomatous neoplasms.

Well-differentiated liposarcoma/atypical lipomatous tumor and dedifferentiated liposarcoma can be difficult to distinguish from benign lipomatous neoplasms and other high-grade sarcomas, respectively. Cytogenetics in these tumors has identified ring and giant chromosomes composed of 12q13-15 amplicons including the MDM2 gene. Identifying MDM2 amplification by fluorescence in situ hybridization may prove an adjunctive tool in the diagnosis of lipomatous neoplasms.