Glial fibrillary acidic protein expression is an indicator of teratoma maturation in children.

BACKGROUND The present diagnosis of teratomas is limited to visual examination of their tissues. For the sake of treatment, teratomas are graded according to degrees of nerve tissue maturation. Mature fetal nerve tissue contains the astrocyte-specific intermediate filament protein, the glial fibrillary acidic protein (GFAP). This study aimed to investigate GFAP expressions in the nerve tissue of immature and mature teratomas, and to evaluate if GFAP is indicative of teratoma maturation in pediatric patients. METHODS Nerve tissue specimens were collected from immature (10 children) and mature teratomas (45 children). Nerve tissue specimens as a control group were taken from 33 children with neuroblastoma. GFAP expression of the specimens was studied by immunohistochemical and semi-quantitative analyses. RESULTS GFAP expression was low in the nerve tissue of immature teratomas and high in that of mature ones. A semi-quantitative analysis confirmed statistically significant difference between the GFAP expressions of immature and mature teratomas (P=0.0001). CONCLUSION GFAP is highly expressed in the nerve tissue of mature teratomas and low in that of immature ones, suggesting that the GFAP expression is a meaningful indicator of teratoma maturation. It is helpful for pathologists to diagnose and classify teratomas.