Cribriform neuroepithelial tumor in the third ventricle: a case report and literature review.

Cribriform neuroepithelial tumor (CRINET) is a very rare and recently described entity of INI1-deficient intraventricular neuroepithelial tumor of primitive non-rhabdoid cells with distinct cribriform formation and has a relatively favorable prognosis. A 14-month-old boy had presented with gait imbalance and was crawling for the last 2 weeks. MRI revealed a large, complex solid and cystic mass with dimensions of 55 × 55 × 50 mm in the vicinity of the third ventricle. Histopathologically, the tumor was composed of relatively small undifferentiated neuroepithelial cells arranged in a cribriform pattern and intervening solid sheets with true rosettes. Immunohistochemically, the tumor cells showed complete loss of nuclear INI1 expression and distinct expression of epithelial membrane antigen (EMA) along the luminal borders of the tubules or glands. The typical rhabdoid feature of tumor cells was absent. Ultrastructurally, the tumor cells were neuroepithelial cells that contained short linear rough endoplasmic reticula and distinct intercellular junctions. Here, we describe a new case of CRINET and also discuss its clinicopathological, immunohistochemical, and ultrastructural features.