SMALL ROUND-CELL TUMORS OF BONE AND SOFT-TISSUE - A MORPHOMETRIC AND STEREOMETRIC COMPARATIVE-ANALYSIS OF 119 CASES

OBJECTIVE: To analyze the discriminative capability of morphometric as sessment of nuclear morphology in the differential diagnosis of small round blue call tumors (SRCTs) of bone and soft tissue. STUDY DESIGN: The study material consisted of glutaraldehyde-fixed, resin-embedded, semithin sections from 119 human tumors. Nuclear area, perimeter, maxi mum diameter, form factors and nuclear density were measured in at lea st 300 nuclei per case. RESULTS: Neuroblastoma (NB) (10 cases) showed the most regular pattern. Ewing's sarcoma (ES) (35 cases); atypical Ew ing's sarcoma (AEs) (15 cases) and peripheral neuroectodermal tumors ( PNET) (30 cases) showed no significant differences regarding area, per imeter or form factors, but AEs showed a lower mean nuclear density th at was statistically significant. Rhabdomyosarcomas (16 cases) and ost eosarcomas (OS) (11 cases) were used as controls and showed several mo rphometric and stereometric differences with other SRCTs, whereas micr ocellular OSs (6 cases) shared features of SRCTs and conventional oste osarcomas. CONCLUSION: Morphometric characterization of nuclear featur es reveals differences between the distinct groups of SRCTs. Although overlapping occurred between all these groups at the individual case l evel, this study provides new support for the existence of morphologic links within the family of ES and PNET.