Diagnostic utility of molecular and cytogenetic analysis in lipoblastoma: a study of two cases and review of the literature

Abstract

Lipoblastoma is a benign neoplasm of embryonic white fat tissue that results from the proliferation of primitive adipocytes, in which histological features can be ambiguous. In order to discriminate between lipoblastoma and other lipogenic and lipomatous tumours, we studied chromosomal alterations and protein expression in two cases of lipoblastoma in infants. Standard cytogenetic analysis, fluorescence in-situ hybridization, array comparative genomic hybridization and Western blotting allowed us to demonstrate the presence of chromosome abnormalities involving the 8q11-13 region containing the pleomorphic adenoma gene 1 (PLAG1), which are classically reported in lipoblastoma, and aberrant expression of PLAG1. This report illustrates two different tumorigenic pathways implicating PLAG1 in lipoblastoma: amplification through multiple copies of a small marker chromosome derived from chromosome 8, and a paracentric inversion of the long arm of chromosome 8. Both these anomalies induced aberrant expression of PLAG1, emphasizing the role of PLAG1 in tumorigenesis. The aberrant expression of PLAG1 protein has been hypothesized, but this is the first report to demonstrate its occurrence in lipoblastoma.