Histopathological features and grading in rhabdomyosarcomas of childhood.
Rhabdomyosarcoma represents a large group of soft tissue sarcomas displaying heterogeneous histopathological features. In addition to their histopathological classification, the variable expression of a number of histopathological features may contribute to the heterogeneity and may be related to prognosis. Tissue sections of 113 well-documented, protocol-treated patients with long term follow-up (mean 6 years) were analysed by a panel of four paediatric pathologists. The following features were assessed: presence of rhabdomyoblasts, degree of maturation of rhabdomyoblasts, heterogeneous maturation patterns, mitotic activity, tumour necrosis, myxoid component, and septa. A scoring system was allocated to each index. High degree of maturation (amount of cytoplasm greater than surface area of the nucleus), absence of tumour necrosis (< 10% of tumour surface), and absence of septa (< 10% of tumour surface) significantly correlated with a favourable clinical course. Reproducibility in the assessment of these three features was good: mean kappa varying from 0.53 to 0.64. A rhabdomyosarcoma score function for survival was defined by: (-0.27 x degree of maturation score) + (0.007 x percentage septated area) + (0.031 x percentage tumour necrosis). Based on the score a two-grade system was elaborated, i.e. grade I (score < -0.20) v. grade II (score > or = -0.20). Rhabdomyosarcoma grade appeared to be the best factor in predicting patients survival: 69% long-term survival in patients with grade I v. 33% in patients with grade II (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Wijnaendts
L C
LC
Department of Pathology, Free University of Amsterdam, The Netherlands.
van der Linden
J C
JC
Van Unnik
A J
AJ
Delemarre
J F
JF
Voute
P A
PA
Meijer
C J
CJ
D000293:Adolescent; D002454:Cell Differentiation / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D012208:Rhabdomyosarcoma / Q000401:mortality* / Q000473:pathology*; D018232:Rhabdomyosarcoma, Alveolar / Q000401:mortality / Q000473:pathology; D018233:Rhabdomyosarcoma, Embryonal / Q000401:mortality / Q000473:pathology; D015996:Survival Rate