Genetics of brain tumors
J. K. Cowell in Molecular Genetics of Cancer, 2003
Meningiomas are slow-growing neoplasms derived from the meningothelial cell which forms the arachnoid membrane. These tumors are composed of swirling sheets of cells with oval nuclei, often forming whorls and psammoma bodies. They are generally considered to be benign, because they can often be completely excised surgically, but occasional cases recur and can show aggressive clinical characteristics. SEER data indicate an age adjusted incidence of 0.13 per 100 000 although data reported by CBTRUS support a much higher incidence of 2.5 per 100 000 (CBTRUS, 1995; Stevens et al., 1991). Schwannomas are benign neoplasms, derived from the Schwann cell which forms myelin in the peripheral nervous system. They are found attached to cranial or peripheral nerves, with favored sites being the acoustic and other sensory nerves. CBTRUS data report an overall incidence of nerve sheath tumors of 0.7 per 100 000 (CBTRUS, 1995; Stevens et al., 1991). Histologically they form masses of spindle-shaped cells and are usually benign. Both schwannomas, particularly bilateral lesions involving the acoustic nerves, and meningiomas are components of central neurofibromatosis or NF Type 2 and peripheral schwannomas occur in peripheral neurofibromatosis or NF Type 1.
Tumours of the Parapharyngeal Space
John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford in Head & Neck Surgery Plastic Surgery, 2018
Schwannomas are benign neurogenic tumours considered to originate from either Schwann cells or fibroblasts supporting the nerve. They present in patients between 30 and 70 years of age. They usually arise from either the vagus nerve or the sympathetic trunk. The vagus nerve is reported to be the origin of 50% of parapharyngeal schwannomas and cervical sympathetic chain is the next common source. Generally, schwannomas are characterized by slow and asymptomatic growth. However, progressive growth in the parapharyngeal region may result in pressure effects and cause dysphagia and hoarseness of voice. The pre-operative evaluation is critical, with imaging modalities like CT and MRI determining the diagnosis9 and may indicate the nerve of origin.10 These tumours are usually fusiform along the long axis of the nerve or may be round. They are of heterogenous signal intensity with hypointense, isointense and hyperintense areas on CT and MRI. Transcervical or transoral biopsy of parapharyngeal space schwannomas is usually associated with unique pain not usually reported by patients undergoing fine-needle aspiration biopsy and may be complicated by haemorrhage, infection and rarely cranial nerve injury.
Neurogenic tumors
Eckart Haneke in 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.
Laparoscopic nephrectomy for giant benign renal schwannoma: a case report and review of literature
Published in The Aging Male, 2020
Chao Wang, Wuyue Gao, Sun Wei, Wu Ligao, Liu Beibei, Liu Jianmin, Yang Xiaohuai, Guo Yuanyuan
Schwannoma, also known as neurilemmoma, is an uncommon peripheral nerve tumor originated in Schwann cells. Most schwannomas are benign and locate in different regions of the body, including head, neck, limbs, skull and so on. However, renal or retroperitoneal schwannoma is rarely found, which accounts for only 1–3% of schwannomas and 1% retroperitoneal tumors cases [1]. Preoperative diagnosis is very difficult because of lacking characteristic presentations on symptoms, physical and imagological examination. Tumor excision and postoperative pathological examination are essential to diagnose schwannomas. Here, we report a rare case of giant and complicated renal schwannoma, which was treated successfully by laparoscopic nephrectomy, meanwhile, we present a review of relative literation.
Accelerated growth of orbital schwannomas during pregnancy does not correlate with sex hormone- or growth factor receptor status
Published in Orbit, 2021
G. J. Hötte, N. Meijer, R. M. Verdijk, D. Paridaens
Most orbital schwannomas originate from the ophthalmic division of the trigeminal nerve and are commonly located in the superior orbit due to the nerve distribution pattern.2,3 It presents unilaterally, although there has been one report of bilateral orbital schwannoma.4 When small they are asymptomatic, but usually tend to grow over months to years, causing a slowly progressive exophthalmos and inferior displacement.3,5 Other clinical symptoms are also aspecific and include diplopia and motility disorders, visual loss, scotomas and eyelid swelling.3 Although they are usually painless, a deep, dull pain or sensibility disorder may occur in the distribution of the affected nerve.3 Schwannomas are predominantly benign, and reported cases of malignant transformation are controversial.5 Also, intracranial extension, most commonly through the superior orbital fissure, can occur.2
Distinguishing Benign from Malignant Circumscribed Orbital Tumors in Children
Published in Seminars in Ophthalmology, 2018
Yufei Tu, Frederick A. Jakobiec, Katherine Leung, Suzanne K. Freitag
Typically, schwannomas (Figure 2) of the orbit demonstrate variable but typically hyperintense T2 signal. Variability in T2 signal intensity can be seen, depending on the prevalence of Antoni A or B patterns.1 Tumors that are in the Antoni A group typically demonstrate on MRI uniformly T2 hypointense signaling. Lesions that are in the Antoni B group can exhibit heterogeneous T2 hyperintense signal, with cavitary change.1 Schwannomas are typically avidly enhancing, although areas of cystic/cavitary change can result in regions of heterogeneous enhancement.1,2 No aggressive osseous destruction of the orbital bone is seen on CT. Rather, schwannomas can result in smooth osseous bowing or expansion. In our patient, the schwannoma demonstrated relatively hypointense signaling on T2, isointensity to brain on T2-weighted images, and minimally hyperintensity to skeletal muscle. This would be consistent with the predominant Antoni A growth pattern. The schwannoma also demonstrates no significant restriction of diffusion. Smooth bowing of the lamina papyracea without aggressive erosion is often present on CT. The encapsulation of the tumor by a perineurium is responsible for its elegant circumscription. In an adult, a circumscribed neurofibroma can pose a diagnostic radiographic challenge, but in a child such a lesion is highly exceptional. Most pediatric neurofibromas are of the plexiform and diffuse types.
Related Knowledge Centers
- Peripheral Nervous System
- Schwann Cell
- Myelin
- Cancer
- Malignancy
- Nerve Sheath Tumor
- Malignant Peripheral Nerve Sheath Tumor
- Neurofibromatosis Type II
- Merlin
- S100 Protein