Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Question #84 Next question Previous question

Answer: (A) Subependymoma.  Level of difficulty: 4 NeuroTest NeuroLearn NeuroHelp

Discussion: 

 Click thumbnails to see pictures.

• Subependymomas are composed of glial tumor cell clusters embedded in an abundant fibrillary matrix with frequent microcystic change. It is a histologic grade I tumor in the WHO classification. Grossly, subependymomas present as firm, lobularted, well-demarcated, whitish nodules. Asymptomatic cases usually do not exceed 1.0 cm in diameter; while tumors that obstruct and cause hydrocephalus usually range from 3-5 cm in diameter. Histologically, the tumors are composed of a uniform population of ependymal cells embedded in a densely fibrillar glial matrix; with groups and islands of cells surrounded by acellular bands of glial fibers (Panel A). Microcyst formation is a common feature as illustrated in this photomicrograph (Panel B). The cells lack pleomorphism (Panel B). Mitoses are rare or absent. Like other ependymal tumors, perivascular coronary arrangements of tumor cells (pseudorosettes) can occur. These arrangements, however, is usually not conspicuous, small, and relatively uncommon. [Click here to see a case of subependymoma]
• Subependymal giant cell astrocytoma (SEGA) also occurs as subependymal exophytic nodules. However, they are composed of giant cells which is in contrast to the small cells illustrated in this case. SEGA also has large, bizarre appearing nuclei. In additional, they are almost invariably associated with tuberous sclerosis. [Click here to see a photomicrograph of SEGA]
• Central neurocytoma and cerebellar liponeurocytoma share the features of sheets of polygonal, clear cells with bland, round nuclei. The morphology resemble oligodendroglioma. Cerebellar liponeurocytoma has the additional feature of occurring in the cerebellum and contains mature adipose tissue. These features are not found in the current case. [Click here to see a case of central neurocytoma][Click here to see a case of cerebellar liponeurocytoma]
• Oligodendrogliomas have clear polygonal cells and delicate vascular network. Both featuers are not present in this case. [Click here to see a photomicrograph of an oligodendroglioma]

Comment: KarMing-Fung@ouhsc.edu