Cytomorphologic features of myxopapillary ependymoma: a review of 13 cases.
OBJECTIVE
To describe the cytologic features of myxopapillary ependymoma (MPE) on intraoperative smears, to analyze cytomorphologic parameters that may help in reaching the diagnosis and to discuss differential diagnosis.


METHODS
Touch imprint smears of 13 MPE cases were reviewed and graded semiquantitatively for 14 cytomorphologic parameters; cellularity, myxoid background, isolated/dispersed tumor cells, "hyaline globules (HGs)," fibrillary cytoplasmic processes, papillary structures, perivascular pseudorosettes, epithelioid tumor cells (ETCs), intracytoplasmic mucin, intranuclear inclusions, nuclear grooves, mitosis, cytologic atypia and hemosiderin-laden macrophages.


RESULTS
Cytologic examination revealed variably cellular specimens composed of isolated and loosely aggregated tumor cells with round to oval or occasionally spindle-shaped nuclei; evenly distributed, finely granular chromatin; and fibrillary processes admixed with occasional ETCs. Most of the cases showed prominent fibrillary processes and occasional ETCs with at least a focal myxoid background. HGs and hemosiderin-laden macrophages were often seen. Papillary structure, a histologic hallmark of MPE, was rarely observed.


CONCLUSIONS
Dual glial and epithelioid properties of tumor cells, well-known features of "regular" ependymomas, and a distinctive myxoid background with HGs strongly support a diagnosis of MPE and are of great help in excluding other mimics (e.g., other variants of ependymoma, metastatic mucinous adenocarcinoma, metastatic adenoid cystic carcinoma and chordoma).
Takei
Hidehiro
H
Department of Pathology, The Methodist Hospital, 6565 Fannin Street, Houston, Texas 77030, USA. takei327@aol.com
Kosarac
Ognjen
O
Powell
Suzanne Z
SZ
D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis / Q000556:secondary; D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D003528:Carcinoma, Adenoid Cystic / Q000175:diagnosis / Q000556:secondary; D002467:Cell Nucleus / Q000473:pathology; D016543:Central Nervous System Neoplasms / Q000378:metabolism / Q000473:pathology*; D002817:Chordoma / Q000175:diagnosis / Q000556:secondary; D003937:Diagnosis, Differential; D004806:Ependymoma / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009077:Mucins / Q000378:metabolism; D012189:Retrospective Studies; D055815:Young Adult
D014408:Biomarkers, Tumor; D009077:Mucins