title: Immunohistochemical expression of p16 in lipoblastomas.
abstract: Lipoblastoma (LB) is a rare benign adipocytic tumor of childhood occasionally showing histological similarities to myxoid liposarcoma (ML) or well-differentiated liposarcoma (WDL). p16 immunohistochemistry has proved to be useful in distinguishing various types of liposarcomas, in particular WDL from lipoma, with higher sensitivity and specificity than MDM2 and CDK4 immunohistochemistry. In this study, we reported the histologic features of a series of 30 LB with emphasis on the potential diagnostic pitfalls and investigated the immunohistochemical expression of p16. Moreover, p16 immunostaining was performed in 16 liposarcomas (11 WDL and 5 ML), 16 lipomas, and 16 cases of liponecrosis in order to evaluate its usefulness in the differential diagnosis of challenging lesions occurring in older children. Overall, p16 immunostaining was positive in 3 LBs and in 12 out of 16 liposarcomas (10 WDL and 2 ML), with a sensitivity of 75%, a specificity of 90%, a positive predictive value of 80%, and a negative predictive value of 87%. All lipomas were p16 negative, whereas 5 liponecroses were positive. Accounting altogether the benign lesions versus liposarcomas, p16 showed a sensitivity of 75%, a specificity of 87%, a positive predictive value of 60%, and a negative predictive value of 93%. Our data suggest that a negative p16 immunostaining may be helpful in excluding a liposarcoma when occurring in unusual clinical contexts, such as in adolescence or late recurrence. However, such finding should be interpreted with caution since also some liposarcomas lack p16 and occasional LBs are positive.
authors.affiliation: Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121.
authors.forename: Rocco
authors.initials: R
authors.lastname: Cappellesso
authors.affiliation: Department of Pathology, San Bortolo Hospital, Vicenza (VI), Italy, 36100.
authors.forename: Emanuele S G
authors.initials: ES
authors.lastname: d'Amore
authors.affiliation: Department of Woman and Child Health, Pediatric Surgery Unit, University of Padua, Padua (PD), Italy, 35128.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Dall'Igna
authors.affiliation: Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Guzzardo
authors.affiliation: Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121.
authors.forename: Elisa
authors.initials: E
authors.lastname: Vassarotto
authors.affiliation: Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121.
authors.forename: Massimo
authors.initials: M
authors.lastname: Rugge
authors.affiliation: Department of Medicine, Surgical Pathology & Cytopathology Unit, University of Padua, Padua (PD), Italy, 35121. Electronic address: ral@unipd.it.
authors.forename: Rita
authors.initials: R
authors.lastname: Alaggio
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis*; D004268:DNA-Binding Proteins / Q000235:genetics; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D062689:Lipoblastoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D018208:Liposarcoma, Myxoid / Q000737:chemistry* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results
chemical_list: D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; C104382:PLAG1 protein, human
keywords: Lipoblastoma; Liposarcoma; Myxoid liposarcoma; PLAG1; Well-differentiated liposarcoma; p16