Brain lipid–binding protein: a marker of differentiation in neuroblastic tumors

Abstract

Purpose Neuroblastoma (NB), ganglioneuroblastoma (GNB), and ganglioneuroma (GN) are neuroblastic tumours (NT) of sympathetic nervous system origin. Brain lipid-binding protein (BLBP) has potential morphogenic activity during nervous system development but has not been studied in these tumours. We analyzed the expression of BLBP in NT according to histological subtypes and extent of differentiation. Methods Thirty cases of NT (10 each of NB, intermixed GNB, and GN) were identified from the histopathology archive of a single center. Tissue sections were obtained from representative paraffin blocks and immunohistochemistry for BLBP performed. Results Brain lipid-binding protein was not expressed in any NB case. In all cases of GN, BLBP was strongly expressed in the cytoplasm of mature ganglion cells but negative in Schwannian stroma. In the intermixed GNB, there was similar strong BLBP immunoreactivity in the cytoplasm of fully differentiated and differentiating ganglion cells but no BLBP expression in immature neuroblasts. Conclusion Brain lipid-binding protein is strongly expressed in mature and maturing ganglion cells in NT (GN and GNB), whereas it is absent in poorly differentiated neuroblasts of GNB and NB. Cytoplasmic expression of BLBP in NT increases as the cells undergo neural differentiation and is therefore associated with the extent of tumour differentiation and favorable histology.