Differential diagnosis of atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma: utility of p16 in combination with MDM2 and CDK4 immunohistochemistry.
The differential diagnosis between atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) and dedifferentiated liposarcoma (DDLPS) from their morphologic counterparts is challenging. Currently, the diagnosis is guided by MDM2 and CDK4 immunohistochemistry (IHC) and is confirmed by the amplification of the corresponding genes. Recently, p16 IHC has been proposed as a useful diagnostic biomarker. The objective was to assess the utility of p16 IHC in the differential diagnosis of ALT/WDLPS and DDLPS. Our series included 101 tumors that were previously analyzed using fluorescence in situ hybridization for MDM2 and CDK4 amplification. We compared sensitivity and specificity of p16 IHC to MDM2 and CDK4 IHC in the differential diagnosis of ALT-WDLPS (n=19) versus benign adipocytic tumors (n=44) and DDLPS (n=18) versus mimicking sarcomas (n=20). In the differential diagnosis of ALT-WDLPS, p16 had a sensitivity of 89.5% but a specificity of 68.2%, which was impaired by false-positive lipomas with secondary changes, especially in biopsies. Likewise, in the differential diagnosis of DDLPS, p16 had a sensitivity of 94.4% and a specificity of 70%, which hampered its use as a single marker. However, adding p16 to MDM2 and/or CDK4 increased diagnostic specificity. Indeed, MDM2+/p16+ tumors were all ALT-WDLPS, and MDM2-/p16- tumors were all benign adipocytic tumors. Moreover, all MDM2+/CDK4+/p16+ tumors were DDLPS, and the MDM2-/CDK4-/p16- tumor was an undifferentiated sarcoma. Although the use of p16 as a single immunohistochemical marker is limited by its specificity, its combination with MDM2 and CDK4 IHC may help discriminate ALT-WDLPS/DDLPS.
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France; CNRS/UMR 6290 Biosit, Faculté de Médecine de Rennes 1, 35000 Rennes, France. Electronic address: jacquet.sf@gmail.com.
Solène-Florence
SF
Kammerer-Jacquet
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France.
Sixte
S
Thierry
Service de Cytogénétique et Biologie Cellulaire, CHU Pontchaillou, 35000 Rennes, France; UMR991, Inserm, Foie Métabolisme et Cancer, 35000 Rennes, France.
Florian
F
Cabillic
Service d'Epidémiologie et de Santé Publique, CHU Pontchaillou, 35000 Rennes, France.
Morgane
M
Lannes
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France.
Florence
F
Burtin
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France.
Sébastien
S
Henno
CNRS/UMR 6290 Biosit, Faculté de Médecine de Rennes 1, 35000 Rennes, France; Service de Cytogénétique et Biologie Cellulaire, CHU Pontchaillou, 35000 Rennes, France.
Frédéric
F
Dugay
Service d'Investigation Clinique, CHU Pontchaillou, 35000 Rennes, France; Unité INSERM 1099, Faculté de Médecine, Université de Rennes 1, 35000 Rennes, France.
Guillaume
G
Bouzillé
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France; CNRS/UMR 6290 Biosit, Faculté de Médecine de Rennes 1, 35000 Rennes, France.
Nathalie
N
Rioux-Leclercq
CNRS/UMR 6290 Biosit, Faculté de Médecine de Rennes 1, 35000 Rennes, France; Service de Cytogénétique et Biologie Cellulaire, CHU Pontchaillou, 35000 Rennes, France.
Marc-Antoine
MA
Belaud-Rotureau
Service d'Anatomie et Cytologie Pathologiques, CHU Pontchaillou, 35000 Rennes, France.
Nathalie
N
Stock
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D001706:Biopsy; D054337:Cell Dedifferentiation; D051358:Cyclin-Dependent Kinase 4 / Q000032:analysis* / Q000235:genetics; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008067:Lipoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D008080:Liposarcoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D051736:Proto-Oncogene Proteins c-mdm2 / Q000032:analysis* / Q000235:genetics; D015203:Reproducibility of Results; D055815:Young Adult
D014408:Biomarkers, Tumor; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4
CDK4; Differential diagnosis; Fluorescence in situ hybridization; Immunohistochemistry; MDM2; Well-differentiated/dedifferentiated liposarcoma; p16