Dedifferentiated liposarcoma with homologous lipoblastic differentiation: expanding the spectrum to include low-grade tumours.

[well-differentiated liposarcoma]

Dedifferentiated liposarcoma (DDLPS ) is traditionally defined as a non-lipogenic high -grade sarcoma arising from a well-differentiated liposarcoma that confers metastatic potential . Recently , DDLPSs with lipoblastic differentiation , i .e . morphologically lipogenic DDLPSs , were reported . Because of the lipoblastic differentiation , these tumours caused confusion , and were reported under different names . However , cytogenetic and molecular studies have revealed their DDLPS nature . So far , the cases reported have been high -grade pleomorphic liposarcoma -like tumours . In this study we have collected another series that contains low -grade tumours , and expand the histological spectrum .Eighteen cases of DDLPS with lipoblastic differentiation from various anatomical locations were analysed by routine histology , immunohistochemistry , and MDM 2 fluorescence in -situ hybridization . Two main histological patterns were seen : one featured a spindle cell sarcoma containing lipoblasts with variable nuclear pleomorphism , and the other a pleomorphic liposarcoma -like tumour including the epithelioid variant . Two cases showed low nuclear grade and lipogenic activity in the metastatic foci . CDK 4 , MDM 2 and p 16 (INK ) (4 a ) overexpression was seen in all except one case . MDM 2 amplification was found in all 16 cases tested .We have expanded the spectrum of this variant of DDLPS to include low -grade tumours , in which a careful search for increased mitotic activity is essential . Like conventional DDLPS , these tumours are capable of metastasis .

Diseases
Validation

Diseases presenting "in which a careful search for increased mitotic activity is essential" symptom

dedifferentiated liposarcoma

pleomorphic liposarcoma

well-differentiated liposarcoma

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