Eosinophil infiltrates in pilocytic astrocytomas of children and young adults.
OBJECTIVE
Eosinophils may affect each stage of tumour development. Many studies have suggested that tumour-associated tissue eosinophilia (TATE) is associated with favourable prognosis in some malignant tumours. However, only a few studies exist on TATE in central nervous system (CNS) tumours. Our recent study exhibited eosinophils in atypical teratoid/rhabdoid tumours (AT/RTs), pediatric malignant CNS tumours with divergent differentiation. This study examines eosinophils in pilocytic astrocytomas (PAs).


METHODS
The study included 44 consecutive cases of patients with PAs and no concurrent CNS inflammatory disease.


RESULTS
We found eosinophils in 19 (43%) of 44 PAs (patient age range, 0.5-72 years). Eosinophils were intratumoural and clearly distinguishable. The density of eosinophils was rare to focally scattered. PAs containing eosinophils were located throughout the CNS. Furthermore, eosinophilic infiltration was identified in 18 (62%) of 29 pediatric (age range, 0.5-18 years) PAs but only 1 (7%) of 15 (p<0.001, significantly less) adult (age range, 20-72 years) PAs. Eosinophilic infiltration showed no significant differences between PAs with and without MRI cystic formation, surgical procedures, or PAs with and without leptomeningeal infiltration. In comparison, eosinophils were absent in 10 pediatric (age range, 0.5-15 years) ependymomas (or anaplastic ependymomas).


CONCLUSIONS
These results suggest that eosinophils are common in pediatric PAs but rare in adult PAs. This difference is probably related to the developing immune system and different tumour-specific antigens in children. TATE may play a functional role in the development of pediatric PAs, as well as some other pediatric CNS tumours such as AT/RTs.
1Department of Laboratory Medicine and Pathology,University of Alberta,Edmonton,Alberta,Canada.
Jian-Qiang
JQ
Lu
1Department of Laboratory Medicine and Pathology,University of Alberta,Edmonton,Alberta,Canada.
Omid
O
Rashidipour
2Department of Pediatrics,University of Alberta,Edmonton,Alberta,Canada.
Beverly A
BA
Wilson
3Department of Surgery,University of Alberta,Edmonton,Alberta,Canada.
Andrew S
AS
Jack
3Department of Surgery,University of Alberta,Edmonton,Alberta,Canada.
Jeffrey
J
Pugh
3Department of Surgery,University of Alberta,Edmonton,Alberta,Canada.
Vivek
V
Mehta
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000175:diagnosis* / Q000378:metabolism*; D016543:Central Nervous System Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004804:Eosinophils / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D055815:Young Adult