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 assessment of nuclear morphology in the differential diagnosis of small round blue cell 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, maximum diameter, form factors and nuclear density were measured in at least 300 nuclei per case.

RESULTS

Neuroblastoma (NB) (10 cases) showed the most regular pattern. Ewing's sarcoma (ES) (35 cases); atypical Ewing's sarcoma (AEs) (15 cases) and peripheral neuroectodermal tumors (PNET) (30 cases) showed no significant differences regarding area, perimeter or form factors, but AEs showed a lower mean nuclear density that was statistically significant. Rhabdomyosarcomas (6 cases) and osteosarcomas (OS) (11 cases) were used as controls and showed several morphometric and stereometric differences with other SRCTs, whereas microcellular OSs (6 cases) shared features of SRCTs and conventional osteosarcomas.

CONCLUSION

Morphometric characterization of nuclear features reveals differences between the distinct groups of SRCTs. Although overlapping occurred between all these groups at the individual case level, this study provides new support for the existence of morphologic links within the family of ES and PNET.