Oxidative stress is related to the formation of Antoni B patterns and eosinophilic hyaline droplets in schwannomas

Abstract

Schwannomas, particularly of vestibular origin, often accompany degenerative hypocellular areas known as Antoni B patterns; however, the detailed mechanism is uncertain. Eosinophilic hyaline droplets (EHD), the substantial nature of which are autophagic vacuoles, preferentially appear in acoustic schwannomas and distribute around areas of Antoni B. We investigated their common background using schwannomas with (15 cases) or without (10 cases) EHD, and demonstrated that EHD showed selective immunoreactivity with an anti-nitrotyrosine antibody, suggesting the overproduction of nitric oxide in this condition. The expression of inducible nitric oxide synthase was emphasized in infiltrating macrophages around hyalinized vessels. Protein-bound 4-hydroxy 2-nonenal, another oxidative stress marker, was detected in Antoni B tissue, but not in EHD. Antibodies to cleaved caspase-3 and single strand DNA, indicators of apoptosis, did not label tumors cells in Antoni B areas as well as EHD-bearing cells. The morphology and the mitotically static state of EHD-laden cells are phenotypically similar to autophagic cell death; however, autophagy in normal cells is a cell survival strategy against starvation, so the possibility remains that EHD are formed in that context. In either case, schwannomas may show a characteristic autophagic change by an endogenous mechanism. Tumor growth in a narrow intracranial space and resultant ischemia by self-oppression were postulated to be an initial event, because ischemia-reperfusion injury is a major source of reactive oxygen species and ischemia is also a potent trigger of autophagy as well as of tissue degeneration. Moreover, potential roles of chemokines and hemosiderosis are discussed.

Intra-cerebellar schwannoma with various degenerative changes: a case report and a systematic review

“…In the present case, along with hyalinization of the blood vessels, eosinophilic granular inclusions or hyaline bodies were diffusely observed. Granular inclusions such as those observed in the present case were reported to be frequently observed in intra-cranial schwannomas, especially acoustic schwannomas [19,20], as products of degeneration, and tend to be distributed around the periphery of the Antoni B pattern or area with rich hemosiderin deposition. Pilocytic astrocytoma (PA) should be considered in the differential diagnosis of cerebellar tumors with remarkable degenerative changes.…”

Schwannoma of the lateral nasal wall: A case report

“…It has been suggested that oxidative stress plays a crucial role in the pathogenesis of schwannoma. 11 Based on the review of literature, in some cases of nasal schwannoma, the patient had diabetes mellitus. 8 In our study, the patient had diabetes for 4 years.…”

Schwannoma of the lateral nasal wall: A Case Report

“…In the present patient, nasal cavity schwannoma originated from the lateral nasal wall, and given that the lateral wall is innervated by anterior ethmoidal nerve, lateral posterior inferior nasal, and lateral posterior superior nasal, it seems that aforementioned schwannoma is associated with above nerve, however, due to the complex pathomechanism of schwannoma, it is not possible to make a definite statement about the origin of this type of schwannoma and the issue is open to As previously mentioned, the pathomechanism of schwannoma is very complex and several factors are involved in its development. It has been suggested that oxidative stress plays a crucial role in the pathogenesis of schwannoma (11). Based on the review of literature, in some cases of nasal schwannoma, the patient had diabetes mellitus (8).…”