Intracytoplasmic lumina in ependymomas: An ultrastructural study
Intracytoplasmic lumina (ICL) are round to oval, single membrane bound spaces bearing microvilli that may or may not contain secretory material. The morphogenesis of ICL remains controversial and their biological significance and diagnostic implication of this structure have not been fully explored. ICL have been reported in a variety of epithelial tumors outside the central nervous system, but this structure is rarely described in tumors of the central nervous system.We analyzed ultrastructural features of ICL in six ependymomas (1 from lateral ventricle, 3 from fourth ventricle and 2 from the spinal cord) and three myxopapillary ependymomas of the filum terminale. Two types of ICL were identified: (1) ICL with both microvilli and cilia and (2) ICL with only microvilli (Fig.1). Ciliated ICL were common in ependymomas of the ventricles whereas non-ciliated ICL were frequently seen in myxopapillary variant. Various stages of formation and development were observed in ciliated ICL (Fig. 2,3).