期刊名称：ePlasty: Open Access Journal of Plastic and Reconstructive Surgery
印刷版ISSN：1937-5719
出版年度：2018
卷号：18
语种：English
出版社：Open Science Co. LLC
摘要：DESCRIPTIONA 57 year-old-man presented to the clinic with painless swelling in his right distal volar forearm. His medical history was significant for a previously resected autistic neuroma. Magnetic resonance imaging (MRI) was performed. Two schwannomas were present involving the median nerve (Figs 1aand1b) and a muscular branch of the ulnar nerve to the flexor digitorum profundus (Figs 2aand2b).QUESTIONSHow do schwannomas typically present?Who is at risk of developing schwannomas?How are schwannomas treated?What is the difference in outcomes between neurofibromas and schwannomas?DISCUSSIONSchwannomas are benign tumors that develop from the peripheral myelin-producing cells, the Schwann cells. Schwannomas can present in various locations throughout the peripheral nervous system but are most commonly found in the head and neck, accounting for up to 45% of all schwannomas.1Patients presenting with schwannomas typically complain of chronic neuropathic pain due to the compression of the adjacent nerve. The presence of a noticeable mass is also frequently seen with peripheral tumors.2The diagnosis of schwannoma is made through a thorough history and physical examination and confirmed with imaging, including computed tomography and MRI, and tissue biopsy.3A key examination finding of these tumors is mobility with transverse motion but not in the longitudinal axis. This is due to their nested, intraneural location (Fig 3).3A differential diagnosis should also include neurofibroma, ganglion, sarcoma, lipoma, and xanthomas.3Schwannomas most commonly present within the third to sixth decades of life.3Most are idiopathic; however, they can be associated with genetic disorders. Schwannomatosis is the development of multiple Schwann cell tumors in the periphery.4Schwannomatosis has been shown to have an autosomal dominant inheritance pattern with incomplete penetrance. It is most closely associated with mutations in tumor suppressor genes, includingSMARCB1orINI1.4Schwannomatosis falls under the umbrella of neurofibromatosis (NF), which has 3 distinct disorders: NF type 1 (NF1), NF type 2 (NF2), and schwannomatosis.4Neurofibromas are benign tumors of the nerve sheath and have been previously understood to be isolated from schwannoma formation.4Both NF and schwannomatosis are seen equally in all races and genders. In addition, it is important to note that one type cannot turn into another, although NF2 and schwannomatosis are found on the same chromosome, chromosome 22.4The patient did not carry a diagnosis of NF2 prior to the identification of these tumors but met criteria for NF2 due to his history of acoustic neuroma and 2 additional NF-related tumors (schwannomas).Management of these tumors is based mainly on the severity of symptoms. For those with symptomatic schwannomas, the treatment is surgical. This often involves intraneural dissection requiring meticulous technique to maintain function of the involved nerve.5If the tumor capsule is densely adherent to the parent nerve, it is left behind. Currently, there are no medical treatments of schwannomas.The surgical interventions for neurofibroma and schwannoma vary slightly, as do their outcomes for nerve preservation and recurrence.6Resolution of schwannomas is quite successful, where surgical removal involves little or no injury to the parent nerve.7Recurrence of schwannomas after total removal is rare.8This is due to the structural difference between neurofibromas and schwannomas, the latter being encapsulated and easier to remove with meticulous technique (Fig 4).8On the contrary, neurofibromas are often intimately integrated into the nerve fibers and have a greater potential for lasting nerve damage following resection.8The most common postoperative complication is paresthesia.In summary, schwannomas are uncommon in the upper extremity, accounting for 0.1% to 0.3% of all hand tumors. When present, they may be associated with genetic abnormalities. There is currently no medical treatment of these benign tumors, but surgical outcomes are very positive.3,4
