Intramedullary Clear Cell Ependymoma in the Thoracic Spinal Cord: A Case with Its Crush Smear and Ultrastructural Findings

Abstract

Clear cell ependymoma was included in the World Health Organization classification of the nervous system in 1993, and all the reported cases, except for two in the spinal cord, were located in the brain, mainly in the supratentorial compartment. Astrocytomas outnumber ependymomas in the spinal cord, and the two entities partly share cytologic findings such as long, bipolar glial processes and oval to round nuclei resembling those seen in pilocytic astrocytoma. Here, we report the first Korean case of intramedullary clear cell ependymoma of the spinal cord, which is the third case situated in the spinal cord in the literature. The crush smear revealed round-to-oval nuclei with occasional nuclear eosinophilic inclusion and rare nuclear grooves. Cytoplasm had fluffy eosinophilic glial processes, and acellular fibrillary zone. On hematoxylin-eosin stain, oval to round tumor cells had large central nuclei with indistinct nucleoli and a moderate amount of clear cytoplasm, i.e. perinuclear halo, mimicking oligodendroglioma. Perivascular pseudorosettes and ependymal clefts were rarely found. In retrospect, perinuclear halo was absent on crush smears. Ultrastructurally, they had extensive surface microvilli and edematous cytoplasm filled with abundant glial filaments and microlumens with or without microvilli. Intercellular long cell junctions of the zipper-like zonula adherens type were found.

Crush Cytology of a Primary Intraspinal Rhabdoid Papillary Meningioma: A Case Report

“…Psammoma bodies are not specific for meningioma; they may be found in a variety of tumors such as meningioma, choroid plexus tumors, ependymoma, medulloblastoma, gliofibroma, or even nonneoplastic aging choroid plexus or leptomeninges [28,29]. Intranuclear inclusion is frequently observed in most low-grade meningiomas, but is not specific because intranuclear inclusions or grooves previously described by Kim et al [30] and Kumar [26] can be seen in ependymoma. Of rhabdoid papillary meningiomas, meningioma of rhabdoid component shows abundant eosinophilic cytoplasm, eccentric nuclei and characteristic intracytoplasmic hyaline globules that correspond to paranuclear whorls or bundles of intermediate filaments under electron microscopy.…”

“…Intraoperative frozen diagnosis may sometimes be difficult. Cytologic findings of rhabdoid papillary meningiomas are shared in part with those of spinal cord gliomas and other tumors, such as ependymoma, astrocytoma, astroblastoma and rhabdoid tumors, including atypical teratoid rhabdoid tumor (AT/RT), and even leptomeningeal metastasis of metastatic carcinoma with secondary rhabdoid differentiation [14,23,24,25,26,27,28,29,30,31,32]; therefore, frozen diagnosis of rhabdoid papillary meningioma remains feasible. …”

Analysis of Squash Smear Cytology of Ependymomas

“…The nuclear characteristics seen are the presence of round to oval nucleus with stippled chromatin and 1–3 small nucleoli. Intranuclear grooves described by Kumar [16] and Kim et al [17] and intracytoplasmic lumina described by Otani et al [18] were seen in none of the cases. All the 3 cases of myxopapillary ependymoma showed a myxoid background, papillary structures with myxoid cores.…”

Squash Cytology of a Dural-Based High-Grade Chondrosarcoma May Mimic That of Glioblastoma in the Central Nervous System

“…Low-grade chondrosarcoma should be distinguished from chordoid meningioma, especially when showing frequent nuclear inclusions or grooves as in the present case [15,16,17]. Nuclear inclusions are commonly found in meningioma or ependymoma in intraoperative cytologic smears [1,18,19]. Epithelioid cells having partly vacuolar changes and a myxomucinous gelatinous background are shared features [20].…”