Br. Pawel et al., UNDIFFERENTIATED SARCOMAS OF CHILDREN - PATHOLOGY AND CLINICAL BEHAVIOR - AN INTERGROUP RHABDOMYOSARCOMA STUDY, Medical and pediatric oncology, 29(3), 1997, pp. 170-180
Undifferentiated soft tissue sarcoma (UND-STS) is the most poorly defi
ned tumor eligible for Intergroup Rhabdomyosarcoma Studies (IRS). Rece
nt IRS UND-STS experience was reviewed to assess the histologic charac
teristics and clinical behavior of undifferentiated sarcomas. Of the 1
,527 patients entered on IRS-III and IRS pilot-IV, 96 had tumors class
ified by the IRS Pathology Committee as UND-STS. Of these, 52 had adeq
uate histologic material for this study. After application of immunohi
stochemistry, 18 tumors were reclassified, mostly as embryonal rhabdom
yosarcomas (RMS), primitive neuroectodermal tumors, and intraabdominal
desmoplastic small round cell tumors. The remaining 34 UND-STS had a
diffuse hypercellular histologic pattern made up of sheets of medium-s
ized cells. The tumor cells had a minimal to moderate amount of cytopl
asm and a variable nuclear morphology, predominately vesisular with fi
nely granular chromatin. Except for reactivity with antibodies against
vimentin, most tumors had a negative immunohistochemical profile. The
5 year Kaplan-Meier survival estimate for patients with non-metastati
c disease was 72%, a significant improvement when contrasted with pati
ents diagnosed to have UND-STS in IRS-I and IRS-III. (C) 1997 Wiley-Li
ss, Inc.