Cytomorphologic characteristics, differential diagnosis and utility during intraoperative consultation for medulloblastoma

Objective: To study the cytologic findings that differentiate LC/A and non-LC/A (NLCA) types. Study Design: Cytologic smears, prepared during intraoperative consultation (IOC) of 43 cases of pure histologic type, defined as > 80% of the tumor being composed of 1 of 3 major histologic types-classic, nodular and LC/A-were reviewed and graded semiquantitatively (0-3+) for 14 cytologic features: cellularity, nuclear streaming, endothelial proliferation, necrosis, lymphoglandular bodies, rosette formation, apoptosis, nuclear cannibalism, pleomorphism, macronucleoli, paranuclear inclusions, cytoplasmic vacuoles, mitoses and multinucleation. The grades were compared between the 2 histologic groups, LC/A vs. NLCA, as well as between the preparation methods, squash vs. touch (TP). Values of p < 0.05 were accepted as statistically significant. Results: "Cell wrapping" (cannibalism), pleomorphism, macronucleoli, apoptosis, mitoses and cytoplasmic vacuoles were more significantly observed in LC/A than in NLCA. Conclusion: Intraoperative cytologic evaluation of these cytologic parameters allows distinction between LC/A and NLCA, which can be prognostically useful during IOC. Rosette formation, the histologic hallmark of classic medulloblastoma, is not a discriminator. Given the fewer artifacts and sufficient cellularity, TP is the preferred method of cytologic preparation.