Logistic regression analysis of low grade spindle cell lesions - A cytologic study

OBJECTIVE: To identify key diagnostic cytologic criteria for various low gr ade spindle cell lesions. STUDY DESIGN: We reviewed 20 synovial sarcomas, 18 benign neural tumors, 10 reparative lesions, 24 other benign and 27 additional malignant low grade spindle cell lesions. All specimens were coded as to the presence of absenc e of the following variables: high cellularity, tissue fragments, tissue cu lture appearance, epithelial fragments, vessel fragments, vascular arcades, fibrillar ground substance, myxoid background, microcystic areas, parallel arrangement of nuclei, naked nuclei, single cells, binucleate cells, multi nucleate cells, long filamentous cells, short spindle cells, stellate cells , lipoblasts, nuclear pleomorphism, nuclei with pointed ends, comma/fishhoo k nuclei, cigar-shaped nuclei, ovoid/round nuclei, small nucleoli, large nu cleoli, mitotic figures, intranuclear vacuoles and background histiocytes. A logisitic regression analysis was performed to identify the variables pre dictive of malignant lesions, specifically synovial sarcomas, benign neural tumors and reparative lesions. RESULTS: Statistical analysis selected high cellularity, short spindle cell s, small nucleoli and absence of tissue culture appearance of tissue cultur e appearance as the main criteria for malignant neoplasms. Tissue fragments and high cellularity were selected as the primary criteria and absence of long filamentous cells and of myxoid background as the secondary criteria f or synovial sarcomas. It selected fibrillar ground substance and absence of ovoid/round nuclei as the key criteria for benign neural tumors. The prese nce of a tissue culture appearance was the major criterion for reparative l esions. CONCLUSION: There are many previously described cytologic criteria, but we found that when subjected to statistical analysis, only a few features were significant in the evaluation of low grade spindle cell lesions.