CD34 and microtubule-associated protein 2 expression in dysembryoplastic neuroepithelial tumours with an emphasis on dual expression in non-specific types.

AIMS

Three histological variants of dysembryoplastic neuroepithelial tumour (DNT) have been described, namely, simple, complex and non-specific. However, the concept of non-specific variants of DNT remains controversial, because they cannot be accurately distinguished by histological findings alone from ordinary gliomas. The aim was to characterize further the non-specific histological forms of DNT.

METHODS AND RESULTS

Forty-one DNTs classified as three histological forms were investigated with CD34 and microtubule-associated protein 2 (MAP2) immunohistochemistry. CD34 immunoreactivity was more frequently observed in non-specific DNT types (16/18 cases; 88.9%) than in classic types (6/23 cases; 26.1%) (P < 0.001). Peritumoral CD34 expression of non-neoplastic cells was significantly associated with CD34-positive tumours (20/22 cases; 90.9%) than with CD34-negative tumours (3/19 cases; 15.8%) (P < 0.001). MAP2 positivity in oligodendroglia-like cells or glial elements was significantly different between classic types and non-specific types (P = 0.025). CD34 and MAP2 immunoreactivities were significantly more frequent in non-specific types (83.3%) than in simple (10%) and complex forms (30.8%) (P < 0.001).

CONCLUSIONS

Non-specific DNTs are glioneuronal tumours that have a heterogeneous population of cells with more immature neuronal and glial phenotypes. Furthermore, with regard to practical implications, combined analysis of CD34 and MAP2 is useful in distinguishing DNTs from particularly diagnostically challenging mimics.