Challenging dedifferentiated liposarcoma identified by MDM2-amplification, a report of two cases.

[dedifferentiated liposarcoma]

Liposarcoma is the most frequent soft tissue sarcoma . Well differentiated liposarcoma may progress into dedifferentiated liposarcoma with pleomorphic histology . A minority additionally features myogenic , osteo- or chondrosarcomatous heterologous differentiation . Genomic amplification of the Mouse double minute 2 homolog (MDM 2 ) locus is characteristic for well differentiated and dedifferentiated liposarcomas . Detection of MDM 2 amplification may supplement histopathology and aid to distinguish liposarcoma from other soft tissue neoplasia .Here we present two cases of dedifferentiated liposarcoma with challenging presentation . Case 1 features a myogenic component . As the tumour infiltrated the abdominal muscles and showed immunohistochemical expression of myogenic proteins , rhabdomyosarcoma had to be ruled out . Case 2 has an osteosarcomatous component resembling extraosseous osteosarcoma . The MDM 2 status was determined in both cases and helped making the correct diagnosis . Overexpression of MDM 2 and co -overexpression of Cyclin-dependent kinase 4 is demonstrated by immunohistochemistry . The underlying MDM 2 amplification is shown by fluorescence in situ hybridisation . Since low grade osteosarcoma may also harbour MDM 2 amplification it is emphasised that the amplification has to be present in the lipomatous parts of the tumour to distinguish liposarcoma from extraosseous osteosarcoma .The two cases exemplify challenges in the diagnoses of dedifferentiated liposarcoma . Liposarcoma often has pleomorphic histology and additionally may feature heterologous components that mimic other soft tissue neoplasms . Amplification of MDM 2 is characteristic for well differentiated and dedifferentiated liposarcomas . Determination of the MDM 2 status by in situ hybridisation may assist histopathology and help to rule out differential diagnoses .

Diseases
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Diseases presenting "other soft tissue neoplasms" symptom

dedifferentiated liposarcoma

liposarcoma

well-differentiated liposarcoma

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