Schwannomatosis 1

Alternative Names

  • Neurilemmomatosis, Congenital Cutaneous
  • Neurofibromatosis II
  • NF II
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Other congenital malformations

OMIM Number

162091

Mode of Inheritance

Autosomal dominant

Gene Map Locus

22q11.23, 22q12.2

Description

Schwannomatosis is a rare autosomal dominant disorder characterized by multiple benign tumors that originate from schwann cells. Schwann cells cover the nerves in the peripheral nervous system. Schwannomatosis is a benign homogenous tumor and it consists of only schwann cells. The primary symptom of schwannomatosis is pain in the affected areas, which can be in any part of the body, but it most commonly occurs near the bases of the skull, spine, arms, or legs. In about one-third of the affected patients, schwannomas are restricted to a particular area in the body. As the tumor develops, the pain worsens due to increasing nerve compression. Rarely, the patients affected with schwannomatosis have associated neurologic symptoms including memory loss, vision problems, and weakness. 

Mostly, the cases are of ages between 20 and 40 years, however, schwannomatosis can occur in any age. Males and females are equally affected, and the prevalence is estimated to be 1:2,000,000 individuals. Tumors are detected via X-ray, CT scan, or MRI to establish the diagnosis of Schwannomatosis. Pain medications and surgery is efficient for those patients which enable them to live a healthy life.

Schwannomatosis exhibits an autosomal dominant transmission, however, some cases are found to be sporadic. Most of the patients have shown somatic mutations in a tumor suppressor gene known as neurofibromin-2 (NF2) gene. NF2 gene encodes a cytoplasmic peripheral protein (schwannomin) which interacts with cytoskeleton proteins; therefore, it is important for cellular adhesion. This gene is mapped to the locus 22q12.2. Mutations in SMARCB1 (SWI/SNF Related, Matrix Associated, Actin Dependent Regulator of Chromatin, Subfamily B, Member 1) gene is known to confer susceptibility to the development of schwannomatosis 1.

Epidemiology in the Arab World

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Other Reports

Bahrain

Yousif et al. (2005) described a 35-year-old male with uncommon presentation of Schwannoma in the nasal septum. He presented with a six months history of progressive bilateral nasal obstruction and a noticeable bulge at the caudal end of the nasal septum. He had an itchy sensation in the region overlying the mass. Anterior rhinoscopy revealed a submucosal, smooth firm, non-tender, and freely mobile mass. The mass was approached through a left hemi-transfixion incision, and dissected from the surrounding structures. The excised biopsy was tested histologically showing a typical benign encapsulated Schwannoma with a biphasic arrangement of neoplastic fusiform cells. Few intra-lesion blood vessels with areas of micro-hemorrhage and degenerative micro-cysts formation were noted. The S-100 protein immunoperoxidase stain showed the expected diffuse positive cell membranes and nuclear reactions.

[Yousif H, Rizkalla A, Al-Sindi K. Schwannoma of a nasal septum, uncommon presentation. J Bahrain Med Soc. 2005; 17(2):124-7.]

 

Kuwait

Al Awadhi and Zaid (1990) described three cases of retroperitoneal Schwannoma; two of which were benign and one malignant.

[Al Awadhi, Zaid N. Retroperitoneal Schwannoma report of 3 cases: two benign and one malignant. Kuwait Med J. 1990; 24(2):188-91.]

Oman

Sharma et al. (2000) reported a schwannoma of the deep peroneal nerve in a 52-year-old man who presented with episodes of lancinating pains in the anterolateral aspect of the left leg and foot, with heaviness in the posterior aspect of the thigh. He had earlier presented with a history of intermittent low back pain since the age of 35-years, for which he was managed unsuccessfully as a case of lumbar disc prolapse at L4-L5 level as the MRI revealed degenerative disc changes in the lumbar region with a generalized disc bulge at L4-L5 level but without focal prolapse. He had also been diagnosed with basilar artery thrombosis when he lost his consciousness three years earlier and was put on anticoagulants. He was also a known diabetic and hypertensive on appropriate medications. Neurological examination revealed residual mild left facial palsy with normal higher functions, fundi and other cranial nerves. He was also found to have generalized hypertonia, hyperreflexia, right upgoing but left equivocal plantar responses, with weak dorsiflexion of the left foot and restricted straight leg-raising test on the left side due to the pain. A tender small swelling (6-8mm) was found on the left mid-leg manipulation of which triggered the pains. This swelling was found to be attached to the lateral aspect of the deep peroneal nerve (to its fibre fascicle) on surgical exploration which was completely excised with preservation of the nerve and schwannoma was diagnosed on histopathological examination. Postoperatively, the patient's pain improved with regaining of normal dorsiflexion of the foot and three years later, he was asymptomatic.

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