Eosinophil Infiltrates in Pilocytic Astrocytomas of Children and Young Adults

Abstract

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. RÉSUMÉ: Infiltrats éosinophiles dans les astrocytomes pilocytiques de l'enfant et du jeune adulte. Objectif: Les éosinophiles peuvent influencer chaque stade de l'évolution tumorale. Selon plusieurs études, l'éosinophilie tissulaire associée à certaines tumeurs malignes (ÉTAT) comporterait un pronostic favorable. Cependant, peu d'études sur l'ÉTAT de tumeurs du système nerveux central (SNC) ont été réalisées. Nous avons démontré récemment la présence d'éosinophiles dans des tumeurs tératoïdes/rhabdoïdes atypiques (TT/RA), des tumeurs malignes du SNC chez l'enfant avec différentiation divergente. Cette étude examine la présence d'éosinophiles dans les astrocytomes pilocytiques (APs). Méthode: Nous avons étudié 44 patients consécutifs atteints d'un AP, sans maladie inflammatoire concomitante du SNC. Résultats: Nous avons retrouvé des éosinophiles dans 19 (43%) des 44 AP. L'âge des patients atteints de ces tumeurs allait de 0,5 à 72 ans. Les éosinophiles étaient intratumoraux et clairement identifiables. Leur densité était variable, parfois rares ou en foyers dispersés. Les AP contenant des éosinophiles étaient localisés dans tout le SNC. De plus, une infiltration par des éosinophiles a été observée dans 18 (62%) des 29 AP chez les patients d'âge pédiatrique (écart de 0,5 à 18 ans), mais...

Toxoplasmosis of the central nervous system: Manifestations vary with immune responses

“…There are only occasional case reports of patients showing an association between the CSF/peripheral eosinophilia and brain toxoplasmosis, but these studies lack the CNS tissue examination [26]. As eosinophils rarely infiltrate into the CNS parenchyma (except perivascular and/or hemorrhagic areas) [27], the role of eosinophil infiltration in the CNS toxoplasmosis may be limited and requires further investigation. TG infection elicits generation of CD4+ and CD8+ T-cells that provide protective immunity, but the presence and frequency of these immune cells including DCs and CD8+ T-cells may be dynamic during toxoplasmosis [28].…”