[398] Evaluation of Intraoperative Cytology Preparations (ICP) To Differentiate Central Neurocytoma (CN) from Oligodendroglioma (OL) and Ependymoma (EL)

LE De Las Casas, D Boman, M Gokden. Texas Tech University Health Science Center, El Paso, TX; University of Arkansas for Medical Sciences, Little Rock, AR

Background: ICP are used as rapid complements to frozen section examination during intraoperative evaluation of brain tumors. CN is an uncommon discrete intraventricular round cell neoplasm, typically located in the foramen of Monro. In spite of CN's peculiar intraventricular location, the cellular monotony, and vascular network make its distinction from OL and EP, tumors that can involve periventricular areas, a diagnostic dilemma during intraoperative consultations. This distinction is underscored by different critical extent of surgical resections according to the gross-total resectability of the tumor type. The aim of this study is to identify which ICP features can help to distinguish CN from its two mimickers: OL and EP.
Design: All intraoperative cytology preparations of proven cases of CN, OL, and EP between January, 2001 and March 2009 were retrieved. Four cases of CN, six OL, and four EP, all WHO grade II, were independently examined by two cytopathologists blinded to the diagnoses. All diagnoses were confirmed by tumor tissue sections examination by neuropathologists. All CN cases were further supported by synaptophysin or neuron-specific enolase, and glial fibrillary acidic protein immunostains. The following parameters were evaluated: neuropil, nuclear roundness, nuclear monotony, cellular cohesiveness, vascular network, chromatin density, nucleoli, perivascular and fibrillary rossetes, type of cytoplasmic processes, nucleus to cytoplasm ratios, entrapped glia or neurons, and microcalcifications. Statistical discriminant analysis was performed to analyze the findings.
Results: Statistical analysis revealed 100% congruence (0% misclassification) on the presence of either neuropil or diffuse nuclear monotony (less than 10% tumor cell anisocytosis) to distinguish CN from OL and EP in ICP. Similarly, the presence of short straight capillaries combined with absence of neuropil and diffuse nuclear monotony identified OL; while the lack of short straight capillaries, neuropil, and diffuse nuclear monotony indicated EP.
Conclusions: The presence of neuropil and diffuse tumor nuclear monotony in ICP can be used to distinguish CN from OL, and EP. Alternatively, the absence of these two parameters and the presence of short straight capillaries indicates OL, while the absence of these three parameters identifies EP. ICP can be a valuable aid in differentiating among CN, OL, and EP.
Category: Cytopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 72, Wednesday Afternoon


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