Crush Cytology Features and Differential Diagnosis of Meningiomas and Schwannomas in Central Nervous System

Kim, Young Ju; Jeon, Mi Yeong; Yang, Young Il; Kim, Chan Hwan; Yoon, Hae Kyoung; Khang, Shin Kwang

Abstract

This study was performed in order to evaluate the usefulness of the crush cytologic features and differential diagnosis between meningiomas and schwannomas in the central nervous system. Deeply seated and unusually located meningiomas and schwannomas with equivocal or erroneous frozen section diagnosis can be correctly diagnosed cytologically in crush preparations. Twenty-four meningiomas and nine schwannomas were studied by frozen section and crush preparation technique. These tumors displayed distinctive cytologic features. In meningiomas, the tumor tissue fragments were easy to crush, and the tumor cells were arranged in small clusters, flat sheets, papilla-like, whorling pattern or singly. Individual tumor cells displayed round or oval nuclei with finely granular chromatin pattern and inconspicuous small nucleoli. Occasionally psammoma bodies, nuclear pseudoinclusion or nuclear grooves were found. In schwannomas, tissue fragments were hard in consistency and difficult to crush. The crushed tissue presented as thick, irregular fragments with sharp borders. The cells showed ill-defined cytoplasm and round, oval, cigar-shaped or curved nuclei. It is important to emphasize that the smear pattern under low-power view and cytologic features are helpful in discriminating between these two tumors.