[Segmental schwannomatosis in upper-extremity: 5 cases report and literature review].

OBJECTIVE: Multiple schwannomas localized in a single body part not crossing the midline constitute a rare variant of neurofibromatosis, segmental schwannomatosis. We report our experience with 5 cases of segmental schwannomatosis of the upper extremity and review the related literature to improve our skills in diagnosis and differentiation. METHODS: Five patients with segmental schwannomatosis received surgical treatment in our department from 2003 to 2012, of whom 4 were female and the other one male. The mean age was 38 years, ranging from 29 to 48 years. In retrospect, we discussed the clinical appearance, histologic characteristics, genetic data and surgical management. RESULTS: A total of 351 patients with schwannomas were treated in the recent decade. There were 326 patients with solitary schwannoma, accounting for 92.88%, 25 with neurofibromatosis type 2 (NF-2), occupying 7.12% and 5 with segmental schwannomatosis representing 1.42% of the total. Schwannomas are limited in one upper extremity and randomly located at ulnar nerve, median nerve and radial nerve and their branches, with no obvious predisposition. Their family history was negative for cutaneous tumors or central nervous system disease. Neurological examinations did not reveal symptoms related to vestibular nerves or optic nerves, which excluded NF-2 preliminarily. The prior symptom of three cases was pain which could be irradiated to the nerve distribution area. No pain but slight numbness was found in two cases. MRI disclosed multiple masses along the course of the nerves. They were isointense to muscle on T1-weighed images and hyperintense to subcutaneous fat on T2-weighed images. All schwannomas were resected and histological sections exhibited a characteristic feature of schwannoma. Follow-up work of 4.5 years was done to 4 cases and no recurrence or impairment of nerves was found. CONCLUSION: Segmental schwannomatosis is characterized by multiple schwannomas localized in one limb (upper extremity in our cases) without vestibular nerve tumors, most frequently seen in females at the age of 30-60 years. Segmental schwannomatosis is rarely seen in the previous literature. We found around 20 cases in English articles and no cases in domestic articles. In consideration of the clinical appearances of these 5 cases and the genetic research in the related literature, we recommend that segmental schwannomatosis is a distinct form of neurofibromatosis which needs to be more studied. We should also pay more attention to differentiating this disease from other forms of neurofibromatosis.

Schwannomatosis: a new member of neurofibromatosis family.

BACKGROUND: Schwannomatosis is a recently recognized peripheral nerve polyneoplasm with clinical characteristics and a genetic background that differ from those of neurofibromatosis 2 (NF2). The diagnostic and treatment criteria of this rare disorder are herein discussed. METHODS: The data of 180 patients who underwent operations for benign schwannomas from 2003 to 2012 in our center were reviewed. Eight of them were classified as schwannomatosis according to the diagnostic criteria suggested by MacCollin. The demographic characteristics were documented and compared between the two groups of patients. The patients' clinical presentations, imaging characteristics, histological features, and treatment results were retrospectively investigated and summarized. RESULTS: Of the 180 cases of benign schwannomas we reviewed this time, eight patients presented with schwannomatosis (4.44%). The mean age of the two groups was not significantly different (40.0 vs. 44.7 years, t = 0.88, P = 0.378). However, schwannnomatosis seems to more generally occur in females (75% vs. 48% were females, P = 0.162), although the difference was not statistically significant. The initial main symptom was pain. The neurological examination was otherwise normal. Magnetic resonance imaging (MRI) revealed multiple discrete, well-defined round, or oval lesions distributed along the course of the peripheral nerves in the extremities with low-to-intermediate signal intensity on T1-weighted images and high-signal intensity on T2-weighted images. Vestibular schwannomas were excluded in four patients by cranial MRI. The lesions in all patients were resected and were pathologically proven to be schwannomas. The average follow-up period was 26 months. Six individuals obtained a good result without symptoms or function loss. CONCLUSIONS: Schwannomatosis is characterized by the development of multiple schwannomas without evidence of the vestibular tumors that are diagnostic for NF2. It commonly occurs in middle-aged females. It has similar demographic features to solitary benign schwannoma. Surgical resection always results in a good outcome.