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Neuropathology Of Neuro-Ophthalmic Disorders
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Schwannoma is a slow-growing, benign nerve sheath tumor accounting for less than 1% of the orbital tumors and arises from branches of nerves traversing the orbit such as oculomotor, trochlear or abducens.36–38 Due to complexity of orbital structures, it's difficult to point out the origin. Small tumors are asymptomatic, but as they grow they compress the nerve in which they arise and also the surrounding structures. Most of the patients are adult and proptosis is the commonest presentation. Lid swelling is another prominent feature. MRI is very sensitive neuro-imaging technique for diagnosis. Macroscopically, a schwannoma appears encapsulated mass with a homogeneous, grayish-white cut surface, which may contain areas of hemorrhage. Histologically, schwannoma shows hypo- and hypercellular areas (Figure 25.18a). The cells show nuclear palisading and Verocay body formation (Figure 25.18b). The individual cells show spindle-shaped nuclei with pointed ends. These cells express S-100 protein on immunostaining. Mitosis and necrosis are rarely found. Hyalinized blood vessels as well as secondary degenerative changes such as edema, variable cystic degeneration, and infiltration by foamy macrophages are common findings. Orbital schwannomas often extend into cavernous sinus. A complete surgical excision is usually curative.
Neurogenic tumors
Published in Eckart Haneke, Histopathology of the NailOnychopathology, 2017
Schwannoma is a well-circumscribed Schwann cell tumor that often displaces its nerve to the periphery. Two patterns are differentiated: In the Antoni A type, uniform spindle cells are arranged back to back and each cell is surrounded by a delicate basement membrane identified by PAS staining. These cells cluster in stacks with their nuclei often forming columns. Two neighboring palisades with the intervening Schwann cell cytoplasm form a Verocay body; this pattern was also seen in a subungual schwannoma. The Antoni B tissue is made up of end to end arranged Schwann cells and single cells that are loosely spaced in a clear or myxoid matrix (Figure 12.5). Vascular changes were not seen under the nail. Immunohistochemically, the Schwann cells are positive for neural markers such as S100, but also for collagen type IV and laminin. The cells in the capsule are positive for EMA. Axons are usually not seen.
Intraparotid facial nerve schwannoma: a 17-year, single-institution experience of diagnosis and management
Published in Acta Oto-Laryngologica, 2019
Shijun Li, Xuguang Lu, Shang Xie, Zimeng Li, Xiaofeng Shan, Zhigang Cai
FNAC is recommended as a highly valuable adjunct with a low risk for preoperative differentiation of benign and malignant parotid gland tumors. However, its accuracy in diagnosing IFNS has been only 22–33% [4,6], possibly because of the absence of Verocay bodies or the presence of only noncharacteristic spindle cells. In our study, two patients underwent preoperative FNAC, and both were precisely diagnosed with schwannomas (Figure 3). A part of Verocay body could be spindle cell nucleus arranged in a swirl. Meanwhile, using the fine needle does not mean just acquiring a handful of tissue volume; in fact, adequate cellular samples for microscopy, an accurate sampling site that can be detected via ultrasound guidance [6], and examination by experienced pathologists can increase the diagnosis rate. Taken together, FNAC seems a promising method for preoperative diagnosis.
Intraparenchymal Schwannoma: A Rare Entity
Published in Neuro-Ophthalmology, 2021
Michael S. Vaphiades, James Hackney
In our patient, the diagnosis of schwannoma was based on the presence of rich, diffuse cytoplasm and nuclear staining with the S-100 marker, and the presence of positive collagen IV staining in a membranous pattern around each individual tumour cell. Collagen IV is a major component of basement membranes, and Schwann cells are known to produce pericellular basal lamina, an ability that is characteristically retained in the neoplastic counterpart.22 Our patient did not display Antoni B tissue but did display Antony A that palisades (Verocay body formation). Intracranial schwannomas are frequently lacking in Antoni B tissue, but often demonstrate some level of Verocay body formation.
Case report of intraventricular schwannoma
Published in British Journal of Neurosurgery, 2019
Adam A. Razak, Gerry M. O’Reilly, Robin Highley, Muhammad M. Hussain
Histology revealed classical features of a schwannoma (see Figure), namely a biphasic architecture with both compacted spindle cells and more loose tissue – Antoni A and B components respectively. There was Verocay body formation in the former. There was hyalinisation of the blood vessel walls and dense pericellular reticulin deposition. A few parenchymal lymphocytes were present and there was some haemosiderin deposition.