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DOI: 10.1016/J.JHSB.2005.10.010
Schwannomatosis: Multiple Schwannomas of the Upper LimbFrom the Department of Plastic Reconstructive & Hand Surgery, Castle Hill Hospital, Cottingham, East Yorkshire, UK Correspondence: Corresponding author. Mr S. Hasham, Flat 2 Lacemakers House, North Road, Nottingham, NG7 1AG, UK. Tel.: +44 115 8447616; fax: +44 1332 254638. E-mail: saiidyhasham{at}hotmail.com
Schwannomas (also known as neurilemmomas) are neoplasms of the peripheral nerve sheaths. They are the most common benign tumour of peripheral nerves, yet they account for only 5% of all soft tissue tumours. Their incidence in the upper limb is variable, as is their clinical presentation. We present an unusual case of multiple schwannomas in the upper limb so that other surgeons can share our experience and suggest the correct diagnosis when confronted with a similar case.
Key Words: schwannomatosis • schwannoma • multiple • magnetic resonance imaging
Schwannomas (neurilemmomas) are the most common neoplasm involving the peripheral nerves, yet they account for only 5% of all soft tissue tumours (Kransdorf, 1995; Myhre-Jensen, 1981). They are usually solitary, but multiple tumours in the extremities have been documented in a few cases (Barre et al., 1987; Isenberg et al., 1994; Leverkus et al., 2003).
A 33 year-old gentleman was referred with several painful lumps in his left hand and forearm. These had been present for the past 3 years but had only recently become symptomatic. He was, otherwise, medically fit with no significant family history. On examination, it was noted that he had three firm and well circumscribed swellings in the palm and a similar lesion on the ulnar border of his index finger. There was the suggestion of a further lesion proximal to the wrist crease, which appeared to be closely related to the median nerve. There was no impairment of function of the upper limb and full neurovascular examination was unremarkable. Provocative tests, such as Tinel’s sign, were negative. No other swellings, or pathognomic features, could be identified elsewhere on the body. Plain radiographs of the hand and wrist were normal. Ultrasound scanning and magnetic resonance suggested that these lesions were slightly cystic in nature and were arising from the tendons rather than the nerves (Fig 1). Explorative surgery was undertaken to obtain a diagnosis. The most proximal lesion was intimately related to the median nerve and consisted of several nodules interconnected with each other (Fig 2). The palmar lesions were found to be arising from the common digital nerve branches of the median nerve (Fig 3). The index finger lesion was attached to the ulnar digital nerve of this finger. Each lesion was enucleated by splitting the nerve fibres longitudinally. Histological examination confirmed the presence of multiple schwannomas and a diagnosis of peripheral schwannomatosis was made. Postoperative recovery was unremarkable, with no loss of function, although the patient did complain of altered sensation along the ulnar border of his left index finger. This had resolved by 3 months, at which time there were no signs of recurrence. The patient was later sent for genetic counselling.
Schwannomas are benign neoplasms of peripheral nerve sheaths. They arise from the proliferation of Schwann cells and are typically encapsulated (Höglund et al., 1997). They can occur anywhere in the soft tissue or the viscera, but are most commonly found within the head and neck, the extremities and the truncal region. Schwannomas of the upper extremity may be found anywhere from the brachial plexus to the hand. They are commonly located on the flexor surfaces as these accommodate the major nerves. Their incidence within the upper limb is variable and ranges from 3% to 19% of all schwannomas (Das Gupta et al., 1969; Phalen, 1976; Stack, 1960). Classically, patients present with a slow growing, mobile, firm and discrete swelling along the course of a nerve. Symptoms are often minimal, apart from the occasional pain, sensory deficiency or paraesthesiae when the lesion attains a size to cause compression of the adjacent nerve fibres of the nerve within which the tumour is growing. (Rinaldi, 1983; White, 1967). Severe neurological dysfunction is uncommon because of the yielding nature of the perineurium. While some nerve fibres are pushed slowly to the periphery of the neoplasm, the majority, are subject to only slight compression and remain unaffected, maintaining their integrity and function. With the paucity of symptoms and, often, the absence of specific signs, schwannomas can pose a diagnostic challenge. In a study by Rockwell et al. (2003), the correct clinical diagnosis was made in only 19% of cases. Ganglion was the most common misdiagnosis. This misdiagnosis was made in 38% of cases in this study and relates to the location, size and pedunculated base which are common to ganglia as well as schwannomas. In one study, imaging with ultrasound, computed tomography and magnetic resonance imaging were only capable of identifying schwannomas in 25% of cases (Kransdorf, 1995). Höglund et al. (1997) were unable to distinguish clearly between schwannomas and neurofibromas with ultrasound. Computed tomography and magnetic resonance imaging are often non-specific in the diagnosis of soft tissue tumours but may be useful in delineating the extent of the swelling. This can be particularly useful when a nerve tumour is not palpable but is suspected from symptoms such as pain and a positive Tinel’s sign. Nerve conduction studies are usually normal, because of the slow growth and infiltrative nature of schwannomas, and help little with diagnosis. Most schwannomas are confirmed at surgery. Schwannomas are usually solitary but can be multiple, with several lesions located along the same nerve or arising in different nerves (Barre et al., 1987; Isenberg et al., 1994; Leverkus et al., 2003). Multiple tumours, should raise the suspicion of familial conditions. The most frequent syndrome associated with multiple schwannomas is neurofibromatosis Type 2 (NF2), which is defined by bilateral vestibular schwannomas. Schwannomatosis appears to be a distinct disease characterized by multiple, pathological, proven schwannomas in the absence of vestibular schwannomas. To differentiate between these two conditions can be difficult since there is a degree of overlap in their presentation. It is especially important to exclude the presence of vestibular tumours since the natural history, treatment and genetic risks of these two conditions differ greatly. The occurrence of other characteristic manifestations of NF2 (such as meningioma or ependymoma) in a patient with multiple, non-vestibular schwannomas is highly suspicious of NF2. However, a thorough clinical evaluation including detailed skull base imaging and ophthalmologic evaluation will clarify the diagnosis in most cases (MacCollin et al., 2005).
Received for publication April 7, 2005. Accepted for publication October 17, 2005.
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Abstract
INTRODUCTION
