Humans ; Liposarcoma/genetics* ; Liposarcoma, Myxoid/genetics* ; Transcription Factor CHOP/genetics*

Objective: To investigate the clinicopathologic and molecular genetic characteristics of myxoid pleomorphic liposarcoma (MPLPS). Methods: Six cases of MPLPS diagnosed and consulted in Fujian Provincial Hospital from 2015 to 2021 were collected for histomorphological observation, immunohistochemistry, and fluorescence in situ hybridization (FISH) detection of DDIT3 (CHOP) gene translocation and MDM2/CDK4 gene amplification. Results: There were four males and two females, aged 26-74 years (mean 53.8 years). The tumor size was 3.8-16.0 cm (mean 11.8 cm). All six cases had similar histopathologic features, showing overlapping histologic morphology of myxoid liposarcoma and pleomorphic liposarcoma. Four cases (4/6) were positive for S-100 protein, and the Ki-67 index was 50%-95%. All cases (6/6) were negative for DDIT3 (CHOP) translocation and MDM2/CDK4 amplification by FISH. TP53 (p.R248w) germline mutation was found in one case. Conclusions: MPLPS is a rare subtype of liposarcoma, characterized by overlapping morphology of myxoid liposarcoma and pleomorphic liposarcoma. Genetically, a few of them have TP53 gene germline mutations, but they lack of DDIT3 (CHOP) translocation or MDM2/CDK4 amplification.
Female ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Liposarcoma/pathology* ; Liposarcoma, Myxoid/diagnosis* ; Male ; Molecular Biology ; Proto-Oncogene Proteins c-mdm2/genetics* ; Translocation, Genetic

Adult ; Base Sequence ; DNA, Neoplasm ; genetics ; Exons ; Female ; Humans ; Liposarcoma ; genetics ; Liposarcoma, Myxoid ; genetics ; Male ; Middle Aged ; Molecular Sequence Data ; Oncogene Proteins, Fusion ; genetics ; Polymerase Chain Reaction ; methods ; RNA-Binding Protein EWS ; genetics ; RNA-Binding Protein FUS ; genetics ; Sequence Analysis, DNA ; Transcription Factor CHOP ; genetics ; Translocation, Genetic

CCAAT-Enhancer-Binding Proteins ; genetics ; Cytogenetic Analysis ; Cytogenetics ; methods ; Extremities ; Humans ; Liposarcoma ; etiology ; genetics ; Liposarcoma, Myxoid ; etiology ; genetics ; Molecular Biology ; methods ; Oncogene Proteins, Fusion ; genetics ; RNA-Binding Protein FUS ; genetics ; Retroperitoneal Neoplasms ; etiology ; genetics ; Ring Chromosomes ; Soft Tissue Neoplasms ; etiology ; genetics ; Transcription Factor CHOP ; Translocation, Genetic

OBJECTIVETo explore the feasibility of detecting FUS-CHOP fusion gene in formalin-fixed, paraffin-embedded tissue and its application in the diagnosis and differential diagnosis of myxoid/round cell liposarcomas (MRCLs).

METHODSForty-four formalin-fixed, paraffin-embedded MRCL samples and 60 control cases (atypical/well-differentiated liposarcoma, pleomorphic liposarcoma, low-grade myofibrosarcoma, etc.) retrieved from the archival files were studied. Nested reverse transcription-polymerase chain reaction (RT-PCR) technique was employed to detect the FUS-CHOP mRNA expression, followed by DNA sequencing confirmation of the PCR product. Housekeeping gene PGK was used to assess the quality of the mRNA templates.

RESULTSPGK mRNA was detected in 93 of 104 tumor cases (89.4%), including 39 MRCLs cases (39/44, 88.6%) and 90% of the negative control cases. Type II FUS-CHOP fusion transcript was successfully detected in 20 out of 39 (51.3%) MRCL cases. Type I FUS-CHOP fusion transcript was not detected in any MRCLs in this study. All 60 negative control cases were negative for the FUS-CHOP fusion gene transcripts.

CONCLUSIONS(1) Nested RT-PCR can be used to detect FUS-CHOP mRNA in formalin-fixed, paraffin-embedded tissues. (2) FUS-CHOP is considered a specific molecular and genetic hallmark for MRCLs. Nested RT-PCR is a sensitive and specific technique in detecting FUS-CHOP gene, and can be used in the diagnosis and differential diagnosis of MRCLs.

Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; Diagnosis, Differential ; Female ; Humans ; Liposarcoma ; metabolism ; pathology ; Liposarcoma, Myxoid ; metabolism ; pathology ; Lower Extremity ; Male ; Middle Aged ; Oncogene Proteins, Fusion ; biosynthesis ; genetics ; Paraffin Embedding ; RNA, Messenger ; biosynthesis ; genetics ; RNA-Binding Protein FUS ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Soft Tissue Neoplasms ; metabolism ; pathology ; Transcription Factor CHOP ; biosynthesis ; genetics