Lipoblastoma-like tumor of the vulva: a clinicopathologic, immunohistochemical, fluorescence in situ hybridization and genomic copy number profiling study of seven cases. (December 2018)

• Record Type: Journal Article
• Authors: Schoolmeester, J.; Michal, Michael; Steiner, Petr; Michal, Michal; Folpe, Andrew; Sukov, William
• Is Part Of: Modern pathology. Volume 31:Number 12(2018)
• Page Start: 1862
• Page End: 1868
• Publication Date: 2018-12
• Subjects: Pathology -- Periodicals; Diagnosis, Laboratory -- Periodicals; Pathologie -- Périodiques; Diagnostics biologiques -- Périodiques; Diagnosis, Laboratory; Pathology; Pathology -- Abstracts; Pathology -- Periodicals; Periodicals; Electronic journals; 616.07
• DOI: 10.1038/s41379-018-0102-y
• Languages: English
• ISSNs: 0893-3952

Abstract

Abstract Lipoblastoma-like tumor of the vulva was first described as a benign mesenchymal neoplasm of adipocytic differentiation having features of lipoblastoma, myxoid liposarcoma, and spindle cell lipoma. Prior studies of lipoblastoma-like tumor have evaluated PLAG1, HMGA2, and RB1 immunohistochemistry andDDIT3 rearrangement status, with results supporting its distinction from lipoblastoma and myxoid liposarcoma. However, absent RB1 expression was reported in a majority of tested cases, suggesting that lipoblastoma-like tumor may have underlying 13q alterations and be related toRB1 -deleted soft tissue tumors. To further understand the molecular genetics of lipoblastoma-like tumor, we examined 7 cases by RB1 immunohistochemistry, DDIT3 andPLAG1 break apart FISH probes, RB1 enumeration FISH probe, and genomic copy number analysis by microarray. Patient age ranged from 21 to 56 years (median 35 years). Clinical follow up was available for 5 patients (71%) ranging 3–264 months (median 74 months). Microscopically, lipoblastoma-like tumor formed large lobules separated by thin and/or thick bands of fibrous tissue and had a prominent network of thin-walled vessels. Each tumor was predominantly composed of spindle cells and lipoblasts with variable quantities of mature adipocytes. RB1 immunohistochemistry exhibited a heterogeneous or "mosaic" pattern of weak and negative nuclear expression in all seven cases.DDIT3 andPLAG1 FISH were negative in each case. No evidence ofRB1 regional gain or loss was identified by FISH. Genomic copy number analysis by chromosomal microarray showed a normal diploid profile in six tumors (86%). One tumor had copy number abnormalities consisting of an 11.9 megabase deletion from 1p13.3 to 1p11.2 and monosomy 14. Although lipoblastoma-like tumor has features of lipoblastoma, myxoid liposarcoma, and spindle cell lipoma, it is genetically different from these tumors. Furthermore, lipoblastoma-like tumor does not appear to have structural abnormalities of 13q resulting in deletion ofRB1 .