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The role of magnetic resonance imaging in the management of peripheral nerve tumours
T H E R O L E OF M A G N E T I C R E S O N A N C E I M A G I N G I N T H E M A N A G E M E N T OF P E R I P H E R A L N E R V E T U M O U R S T. E. J. HEMS, P. D. BURGE and D. J. WILSON
From the Nuffield Orthopaedic Centre, Oxford, UK Fourteen cases of peripheral nerve tumour which had been examined by MRI were reviewed. Tl-weighted images showed the tmnours to be of intermediate signal and T2-weighted images showed a high signal with some heterogeneity. These appearances are not specific to peripheral nerve tumours, although the diagnosis may be suggested if the lesion arises from a major nerve trunk. The association with a nerve trunk may be defined by MRI, thus assisting with surgical planning. Neurilemmomas, neurofibromas and malignant nerve sheath tumours could not be differentiated with certainty using MR alone. The MR features of lipofibromatous hamartoma are reported.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 1:57-60 Tumours of peripheral nerves are uncommon; the incidence is approximately 1 per 100,000 population per year. When the tumour arises from a major nerve trunk, careful management is important to reduce the risk of neurological damage at operation. The risk is minimized when the diagnosis is made prior to surgery, allowing the clinical team to select a surgeon with appropriate microsurgical expertise and equipment. A classification of peripheral nerve tumours is shown in Table 1 (Rosenberg et al, 1991; Seddon, 1972). The majority of tumours are neurilemmomas or neurofibromas. Malignant tumours are very rare, most cases occurring in individuals with neurofibromatosis (NF1). The presenting complaint is usually a swelling. It is unlikely that the diagnosis of a nerve tumour will be suspected unless the patient has other features of neurofibromatosis or a major nerve trunk is involved. In the latter situation, the swelling will be in the line of the nerve. There is often pain with paraesthesia in the distribution of the nerve. Tinel's sign may be elicited by percussion over the swelling but a neurological deficit is unusual. Solitary neurofibromas and neurilemmomas produce the same symptoms and signs. If the tumour does not involve a major nerve, then excision biopsy is relatively simple. When a neurilemmorea arises in a major nerve trunk the fascicles run around the mass and it is usually possible to shell out the tumour sacrificing only one or two fascicles (Fig 1). Function of the nerve is largely preserved. In contrast, neurofibromas diffusely involve the nerve trunk. In order to achieve excision, all or. part of the nerve will have to
be sacrificed and reconstruction undertaken with nerve grafts. For this reason, excision of a neurofibroma from a major nerve is rarely justified. Biopsy may be performed to confirm the diagnosis. In a review of 104 cases of solitary benign peripheral nerve tumours, Kehoe et al (1995) reported that a neural tumour had been suspected before operation in only seven cases. Similarly, Holdsworth (1985) found that only in five out of 18 nerve tumours in the upper limb was the diagnosis made before surgery. Both series referred to patients managed before MRI was available. These reports suggest that the diagnosis of a neural tumour is unlikely to be made on clinical assessment alone. Magnetic resonance imaging has been widely available for over 5 years and provides better imaging of many soft tissues than is possible with older techniques. We have reviewed its role in the management of peripheral nerve tumours. METHODS Fourteen patients were identified from pathology and radiology records (Table 2). All had a peripheral nerve
Table 1--Classification of peripheral nerve tumours
Benign Neurilemmoma (Schwannoma) Neurofibroma (Multiple/solitary) Lipoma Lipofibromatous hamartoma Haemangioma
Malignant Fig 1
Primitive neuroectodermal tumour Malignant nerve sheath tumour
57
A neurilemmoma of the ulnar nerve exposed at operation. Nerve fascicles can be seen running over the surface of the tumour.
58
THE JOURNAL OF HAND SURGERY VOL. 22B No. 1 FEBRUARY 1997
Table 2--Details of the cases of peripheral nerve turnouts examined by MRI
Case no.
Age
Site
1 2 3 4 5 6 7 8 9 10
48 48 56 52 61 57 34 50 82 29
*Median n. ( H a n d ) Dorsal forearm *Median n. (Forearm) *Peroneal n. (Fibula neck) Triceps muscle *Ulnar n. (Forearm) Thenar eminence *Ulnar n. (Forearm) *Median n. (Forearm) *Median n. (Arm)
11 12
31 24
*Peroneal n. (Leg) *Tribial n. (Ankle)
13
31
Gluteus maximus
Clinical diagnosis
Neurilemmomas NF, ?Median n. Soft tissue tumour Swelling, median n. Tumour, peroneal n. Soft tissue tumour Tumour, ulnar n. Ganglion Tumour, ulnar n. Tumour, median n. Tumour, median n.
Neurofibromas Soft tissue tumour Neurofibromatosis
Malignant nerve sheath tumour Soft tissue tumour
Lipofibromatous Hamartoma 14
4
*Median n. (Wrist/hand)
Swelling, median n.
* Cases in which the tumour involved a major nerve trunk.
tumour and had undergone examination by MRI. Some patients were also examined by ultrasound either prior to or at the same time as MRI in order to confirm the presence of a solid mass and exclude a cystic lesion. The clinical notes and M R images were reviewed. MRI was performed on an Impact 1.0T (Siemens) with quadrature surface coils. Conventional spin echo, fast STIR and T2-weighted fast spin echo images were performed in planes selected according to the anatomy of each case. Gadolinium-DTPA was not employed routinely. Images were reviewed by a radiologist specialising in musculoskeletal imaging. RESULTS The tumour had been excised or biopsied in 13 out of the 14 patients and the diagnosis confirmed by histological examination. There were ten cases of neurilemmoma, one of neurofibroma, one of malignant nerve sheath tumour, and one of lipofibromatous hamartoma. In the remaining patient, who suffered from neurofibromatosis (NF1), the diagnosis of neurofibroma was presumed. All the patients presented with a swelling. Pain was a prominent feature in four patients. Paraesthesia and Tinel's sign were present in eight cases. Of the ten cases of neurilemmoma, seven arose from a major nerve trunk (Table 2). On the basis of clinical assessment alone, the possibility of a neural tumour had been suspected in all these seven patients, but not in the other three. The tumours were solitary in all but one patient, who was known to have neurofibromatosis. The appearances of the tumours on MRI were non-specific. However, the involvement of a major nerve trunk could be seen in all seven cases, thus confirming the clinical impression of a neural tumour and aiding in the planning
of surgery. It was noted that the original radiologist's report on the MRI did not give this information in three cases. One case of neurofibroma was a solitary tumour involving the branches of the peroneal nerve which had recurred after previous excision. MRI confirmed the relationship to the nerve before surgery. The other neurofibroma occurred at the ankle in a patient with neurofibromatosis (NF1). M R I showed that the tumour arose from the tibial nerve and on this basis a decision was made not to remove it. The appearances of the neurilemmomas and neurofibromas were similar on MRI and the two types of tumour could not be distinguished. On Tl-weighted images the turnouts demonstrated intermediate signal, similar to skeletal muscle, with some inhomogeneity (Fig 2a). On T2-weighted images the lesions showed high signal intensity with areas of lower signal (Fig 2b). The margins were well defined and the relationship between the lesion and adjacent neurovascular structures could be determined. The malignant nerve sheath tumour presented as a painful mass in the buttock. MRI (Fig 3) showed a lesion lying within the gluteus maximus muscle; the appearances were similar to those of benign peripheral nerve tumours. The M R images suggested that the tumour was separate from the sciatic nerve. After needle biopsy, the tumour was excised together with a margin of surrounding muscle, without loss of function of the sciatic nerve. The lipofibromatous hamartoma presented as a soft tissue swelling extending from the distal forearm to the palm, associated with overgrowth of the ring finger. MRI showed a mass lying anterior to the flexor tendons of the fingers (Fig 4). The median nerve could not be identified separate from the lesion. The T1 weighted images showed the lesion to be of similar signal intensity to muscle, while T2 weighted images show a heterogeneous signal intensity with speckled focal areas of high signal. At operation, the carpal tunnel was decompressed and a biopsy was taken from an affected digital nerve. DISCUSSION The M R appearances of our cases of neurilemmoma and neurofibroma are similar to those reported previously (Cerofolini et al, 1991; Stull et al, 1991). The signal intensities on T1 and T2-weighted images are not specific to neural tumours. Many other soft tissue turnouts have a similar appearance, although benign lipomas can be excluded since they show high signal on Tl-weighted images. Therefore the relationship to a nerve is important in suggesting the diagnosis. The involvement of a major nerve trunk strongly influences the management of peripheral nerve tumours and can be predicted from MRI. Cerofolini et al (1991) noted that the nerve lay peripheral to the tumour in neurilem-
MRI AND PERIPHERAL NERVE TUMOURS
Fig 2
M R i m a g e o f a n e u r i l e m m o m a o f the u l n a r nerve. (a) Saggital T l - w e i g h t e d image. (b) A x i a l T2-weighted image.
momas while it was central or obliterated in neurofibromas. They found this relationship useful in differentiating the two types of benign tumour. In our series no reliable distinguishing features were seen on MRI, although the number of neurofibromas was too
59
small to make any definite conclusion. There are no reported M R characteristics which reliably differentiate benign from malignant peripheral nerve turnouts (Stull et al, 1991). Our experience does emphasize the importance of reporting by a specialist radiologist in order to gain the maximum information from the examination. Close cooperation between the surgeon, pathologist and radiologist is essential. As far as ~ve are aware, the M R appearances of lipofibromatous hamartoma have not been reported previously. The term 'lipofibromatous hamartoma' was used first by Johnson and Bonfiglio (1969) to describe a rare condition in which a nerve is enlarged by a diffuse infiltration of fibrous and fatty tissue. The same condition had been reported by Mikhail (1964), Pulvertaft (1964) and Yeoman (1964). The mixture of nerve fascicles, fibrous and fatty tissue explains the heterogeneous appearance on the M R images. Lipofibromatous hamartoma presents in children or young adults and most often affects the median nerve, but has been observed in the ulnar and radial nerves (Rosenberg et al, 1991). The enlargement of the nerve may or may not be associated with macrodactyly of part of the hand. Our case involved mainly the median nerve but there was also involvement of the ulnar digital nerve of the ring finger associated with overgrowth of the finger. The diagnosis of a peripheral nerve tumour was suspected on clinical grounds alone in most of our cases in which a major nerve was involved. This conclusion, based on review of the clinical notes recorded after the patient's first visit to the hospital, is in contrast to the series reported by Kehoe et al (1995) and Holdsworth (1985). Our experience emphasizes the importance of a full history and careful examination. In many cases, appropriate management could have been undertaken without further investigation. However, the availability of images of soft tissues does give the opportunity to confirm clinical impressions, exclude other disease, define anatomy before surgery and plan the operation. When involvement of a peripheral nerve by tumour is suspected on clinical grounds, the most appropriate initial investigation is ultrasound to establish whether the swelling is cystic or solid. If a cystic swelling is found, then surgery will only be indicated if the symptoms warrant excision. MRI may be required to define anatomy. In the case of a solid swelling, biopsy will usually be necessary to establish a diagnosis. In our experience M R I is able to predict or exclude the involvement of major nerves, although the series is too small to define the accuracy of this impression. The histological type of a tumour cannot be defined by MR although the association of a mass with a nerve is strongly suggestive of a neural tumour.
Acknowledgements The authors would like to thank Mr J. S. Watson and Mr P. J. Davenport at Withington Hospital, Dr N. Wright, Radiologist at the Royal Manchester Childrens Hospital, and Mo Al-Qaisi, Research Student at the Nuffield Orthopaedic Centre for advice and allowing us to include their cases. We are
60
Fig 3
THE JOURNAL OF HAND SURGERY VOL. 22B No. 1 FEBRUARY 1997
MR image of a malignant nerve sheath tumour lying in the gluteus maximus muscle. (a) Axial Tl-weighted image. (b) Coronal T2-weighted image.
Fig 4
M R i m a g e o f a l i p o f i b r o m a t o u s h a m a r t o m a o f the m e d i a n nerve. (a) A x i a l T l - w e i g h t e d image. (b) A x i a l T2-weighted image.
also grateful to Mr Paul Cooper at the Nuffield Orthopaedic Centre and the Department of Medical Photography at Withington Hospital for assistance in preparing the illustrations.
References Cerofolini E, Landi A, DeSantis G, Maiorana A, Canossi G, Romagnoli R (1991). MR of benign peripheral nerve sheath tumors. Journal of Computer Assisted Tomography, 15:593 597. Holdsworth BJ (1985). Nerve tumours in the upper limb. A clinical review. Journal of Hand Surgery, 10B: 236-238. Johnson RJ, Bonfiglio M (1969). Lipofibromatous hamartoma of the median nerve. Journal of Bone and Joint Surgery, 51A: 984 990. Kehoe NJS, Reid RP, Semple JC (1995). Solitary benign peripheral nerve tumours. Review of 32 years' experience. Journal of Bone and Joint Surgery, 77B: 497-500. Mikhail IK (1964). Median nerve lipoma in the hand. Journal of Bone and Joint Surgery, 46B: 726-730.
Pulvertaft R G (1964). Unusual tumours of the median nerve. Report of two cases. Journal of Bone and Joint Surgery, 46B: 731-733. Rosenberg AE, Dick HM, Botte MJ. Benign and malignant tumours of peripheral nerve. In: Gelberman RH (Ed.): Operative nerve repair and reconstruction. Philadelphia, JB Lippineott, 1991, Vol. 2: 1587-1625. Seddon HJ. Surgical disorders of the peripheral nerves. Edinburgh, Churchill Livingstone, 1972. Stull MA, Moser RP, Kransdorf MJ, Bogumill GP, Nelson MA (1991). Magnetic resonance appearance of peripheral nerve sheath tumours. Skeletal Radiology, 20: 9-14. Yeoman PM (1964). Fatty infiltration of the median nerve. Journal of Bone and Joint Surgery, 46B: 737-739.
Received: 20 April 1996 Accepted: 4 July 1996 T. E .J. Hems, 24, Ashlong Road, Marston, Oxford OX3 0NH, UK. © 1997 The British Society for Surgery of the Hand
From the Nuffield Orthopaedic Centre, Oxford, UK Fourteen cases of peripheral nerve tumour which had been examined by MRI were reviewed. Tl-weighted images showed the tmnours to be of intermediate signal and T2-weighted images showed a high signal with some heterogeneity. These appearances are not specific to peripheral nerve tumours, although the diagnosis may be suggested if the lesion arises from a major nerve trunk. The association with a nerve trunk may be defined by MRI, thus assisting with surgical planning. Neurilemmomas, neurofibromas and malignant nerve sheath tumours could not be differentiated with certainty using MR alone. The MR features of lipofibromatous hamartoma are reported.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 1:57-60 Tumours of peripheral nerves are uncommon; the incidence is approximately 1 per 100,000 population per year. When the tumour arises from a major nerve trunk, careful management is important to reduce the risk of neurological damage at operation. The risk is minimized when the diagnosis is made prior to surgery, allowing the clinical team to select a surgeon with appropriate microsurgical expertise and equipment. A classification of peripheral nerve tumours is shown in Table 1 (Rosenberg et al, 1991; Seddon, 1972). The majority of tumours are neurilemmomas or neurofibromas. Malignant tumours are very rare, most cases occurring in individuals with neurofibromatosis (NF1). The presenting complaint is usually a swelling. It is unlikely that the diagnosis of a nerve tumour will be suspected unless the patient has other features of neurofibromatosis or a major nerve trunk is involved. In the latter situation, the swelling will be in the line of the nerve. There is often pain with paraesthesia in the distribution of the nerve. Tinel's sign may be elicited by percussion over the swelling but a neurological deficit is unusual. Solitary neurofibromas and neurilemmomas produce the same symptoms and signs. If the tumour does not involve a major nerve, then excision biopsy is relatively simple. When a neurilemmorea arises in a major nerve trunk the fascicles run around the mass and it is usually possible to shell out the tumour sacrificing only one or two fascicles (Fig 1). Function of the nerve is largely preserved. In contrast, neurofibromas diffusely involve the nerve trunk. In order to achieve excision, all or. part of the nerve will have to
be sacrificed and reconstruction undertaken with nerve grafts. For this reason, excision of a neurofibroma from a major nerve is rarely justified. Biopsy may be performed to confirm the diagnosis. In a review of 104 cases of solitary benign peripheral nerve tumours, Kehoe et al (1995) reported that a neural tumour had been suspected before operation in only seven cases. Similarly, Holdsworth (1985) found that only in five out of 18 nerve tumours in the upper limb was the diagnosis made before surgery. Both series referred to patients managed before MRI was available. These reports suggest that the diagnosis of a neural tumour is unlikely to be made on clinical assessment alone. Magnetic resonance imaging has been widely available for over 5 years and provides better imaging of many soft tissues than is possible with older techniques. We have reviewed its role in the management of peripheral nerve tumours. METHODS Fourteen patients were identified from pathology and radiology records (Table 2). All had a peripheral nerve
Table 1--Classification of peripheral nerve tumours
Benign Neurilemmoma (Schwannoma) Neurofibroma (Multiple/solitary) Lipoma Lipofibromatous hamartoma Haemangioma
Malignant Fig 1
Primitive neuroectodermal tumour Malignant nerve sheath tumour
57
A neurilemmoma of the ulnar nerve exposed at operation. Nerve fascicles can be seen running over the surface of the tumour.
58
THE JOURNAL OF HAND SURGERY VOL. 22B No. 1 FEBRUARY 1997
Table 2--Details of the cases of peripheral nerve turnouts examined by MRI
Case no.
Age
Site
1 2 3 4 5 6 7 8 9 10
48 48 56 52 61 57 34 50 82 29
*Median n. ( H a n d ) Dorsal forearm *Median n. (Forearm) *Peroneal n. (Fibula neck) Triceps muscle *Ulnar n. (Forearm) Thenar eminence *Ulnar n. (Forearm) *Median n. (Forearm) *Median n. (Arm)
11 12
31 24
*Peroneal n. (Leg) *Tribial n. (Ankle)
13
31
Gluteus maximus
Clinical diagnosis
Neurilemmomas NF, ?Median n. Soft tissue tumour Swelling, median n. Tumour, peroneal n. Soft tissue tumour Tumour, ulnar n. Ganglion Tumour, ulnar n. Tumour, median n. Tumour, median n.
Neurofibromas Soft tissue tumour Neurofibromatosis
Malignant nerve sheath tumour Soft tissue tumour
Lipofibromatous Hamartoma 14
4
*Median n. (Wrist/hand)
Swelling, median n.
* Cases in which the tumour involved a major nerve trunk.
tumour and had undergone examination by MRI. Some patients were also examined by ultrasound either prior to or at the same time as MRI in order to confirm the presence of a solid mass and exclude a cystic lesion. The clinical notes and M R images were reviewed. MRI was performed on an Impact 1.0T (Siemens) with quadrature surface coils. Conventional spin echo, fast STIR and T2-weighted fast spin echo images were performed in planes selected according to the anatomy of each case. Gadolinium-DTPA was not employed routinely. Images were reviewed by a radiologist specialising in musculoskeletal imaging. RESULTS The tumour had been excised or biopsied in 13 out of the 14 patients and the diagnosis confirmed by histological examination. There were ten cases of neurilemmoma, one of neurofibroma, one of malignant nerve sheath tumour, and one of lipofibromatous hamartoma. In the remaining patient, who suffered from neurofibromatosis (NF1), the diagnosis of neurofibroma was presumed. All the patients presented with a swelling. Pain was a prominent feature in four patients. Paraesthesia and Tinel's sign were present in eight cases. Of the ten cases of neurilemmoma, seven arose from a major nerve trunk (Table 2). On the basis of clinical assessment alone, the possibility of a neural tumour had been suspected in all these seven patients, but not in the other three. The tumours were solitary in all but one patient, who was known to have neurofibromatosis. The appearances of the tumours on MRI were non-specific. However, the involvement of a major nerve trunk could be seen in all seven cases, thus confirming the clinical impression of a neural tumour and aiding in the planning
of surgery. It was noted that the original radiologist's report on the MRI did not give this information in three cases. One case of neurofibroma was a solitary tumour involving the branches of the peroneal nerve which had recurred after previous excision. MRI confirmed the relationship to the nerve before surgery. The other neurofibroma occurred at the ankle in a patient with neurofibromatosis (NF1). M R I showed that the tumour arose from the tibial nerve and on this basis a decision was made not to remove it. The appearances of the neurilemmomas and neurofibromas were similar on MRI and the two types of tumour could not be distinguished. On Tl-weighted images the turnouts demonstrated intermediate signal, similar to skeletal muscle, with some inhomogeneity (Fig 2a). On T2-weighted images the lesions showed high signal intensity with areas of lower signal (Fig 2b). The margins were well defined and the relationship between the lesion and adjacent neurovascular structures could be determined. The malignant nerve sheath tumour presented as a painful mass in the buttock. MRI (Fig 3) showed a lesion lying within the gluteus maximus muscle; the appearances were similar to those of benign peripheral nerve tumours. The M R images suggested that the tumour was separate from the sciatic nerve. After needle biopsy, the tumour was excised together with a margin of surrounding muscle, without loss of function of the sciatic nerve. The lipofibromatous hamartoma presented as a soft tissue swelling extending from the distal forearm to the palm, associated with overgrowth of the ring finger. MRI showed a mass lying anterior to the flexor tendons of the fingers (Fig 4). The median nerve could not be identified separate from the lesion. The T1 weighted images showed the lesion to be of similar signal intensity to muscle, while T2 weighted images show a heterogeneous signal intensity with speckled focal areas of high signal. At operation, the carpal tunnel was decompressed and a biopsy was taken from an affected digital nerve. DISCUSSION The M R appearances of our cases of neurilemmoma and neurofibroma are similar to those reported previously (Cerofolini et al, 1991; Stull et al, 1991). The signal intensities on T1 and T2-weighted images are not specific to neural tumours. Many other soft tissue turnouts have a similar appearance, although benign lipomas can be excluded since they show high signal on Tl-weighted images. Therefore the relationship to a nerve is important in suggesting the diagnosis. The involvement of a major nerve trunk strongly influences the management of peripheral nerve tumours and can be predicted from MRI. Cerofolini et al (1991) noted that the nerve lay peripheral to the tumour in neurilem-
MRI AND PERIPHERAL NERVE TUMOURS
Fig 2
M R i m a g e o f a n e u r i l e m m o m a o f the u l n a r nerve. (a) Saggital T l - w e i g h t e d image. (b) A x i a l T2-weighted image.
momas while it was central or obliterated in neurofibromas. They found this relationship useful in differentiating the two types of benign tumour. In our series no reliable distinguishing features were seen on MRI, although the number of neurofibromas was too
59
small to make any definite conclusion. There are no reported M R characteristics which reliably differentiate benign from malignant peripheral nerve turnouts (Stull et al, 1991). Our experience does emphasize the importance of reporting by a specialist radiologist in order to gain the maximum information from the examination. Close cooperation between the surgeon, pathologist and radiologist is essential. As far as ~ve are aware, the M R appearances of lipofibromatous hamartoma have not been reported previously. The term 'lipofibromatous hamartoma' was used first by Johnson and Bonfiglio (1969) to describe a rare condition in which a nerve is enlarged by a diffuse infiltration of fibrous and fatty tissue. The same condition had been reported by Mikhail (1964), Pulvertaft (1964) and Yeoman (1964). The mixture of nerve fascicles, fibrous and fatty tissue explains the heterogeneous appearance on the M R images. Lipofibromatous hamartoma presents in children or young adults and most often affects the median nerve, but has been observed in the ulnar and radial nerves (Rosenberg et al, 1991). The enlargement of the nerve may or may not be associated with macrodactyly of part of the hand. Our case involved mainly the median nerve but there was also involvement of the ulnar digital nerve of the ring finger associated with overgrowth of the finger. The diagnosis of a peripheral nerve tumour was suspected on clinical grounds alone in most of our cases in which a major nerve was involved. This conclusion, based on review of the clinical notes recorded after the patient's first visit to the hospital, is in contrast to the series reported by Kehoe et al (1995) and Holdsworth (1985). Our experience emphasizes the importance of a full history and careful examination. In many cases, appropriate management could have been undertaken without further investigation. However, the availability of images of soft tissues does give the opportunity to confirm clinical impressions, exclude other disease, define anatomy before surgery and plan the operation. When involvement of a peripheral nerve by tumour is suspected on clinical grounds, the most appropriate initial investigation is ultrasound to establish whether the swelling is cystic or solid. If a cystic swelling is found, then surgery will only be indicated if the symptoms warrant excision. MRI may be required to define anatomy. In the case of a solid swelling, biopsy will usually be necessary to establish a diagnosis. In our experience M R I is able to predict or exclude the involvement of major nerves, although the series is too small to define the accuracy of this impression. The histological type of a tumour cannot be defined by MR although the association of a mass with a nerve is strongly suggestive of a neural tumour.
Acknowledgements The authors would like to thank Mr J. S. Watson and Mr P. J. Davenport at Withington Hospital, Dr N. Wright, Radiologist at the Royal Manchester Childrens Hospital, and Mo Al-Qaisi, Research Student at the Nuffield Orthopaedic Centre for advice and allowing us to include their cases. We are
60
Fig 3
THE JOURNAL OF HAND SURGERY VOL. 22B No. 1 FEBRUARY 1997
MR image of a malignant nerve sheath tumour lying in the gluteus maximus muscle. (a) Axial Tl-weighted image. (b) Coronal T2-weighted image.
Fig 4
M R i m a g e o f a l i p o f i b r o m a t o u s h a m a r t o m a o f the m e d i a n nerve. (a) A x i a l T l - w e i g h t e d image. (b) A x i a l T2-weighted image.
also grateful to Mr Paul Cooper at the Nuffield Orthopaedic Centre and the Department of Medical Photography at Withington Hospital for assistance in preparing the illustrations.
References Cerofolini E, Landi A, DeSantis G, Maiorana A, Canossi G, Romagnoli R (1991). MR of benign peripheral nerve sheath tumors. Journal of Computer Assisted Tomography, 15:593 597. Holdsworth BJ (1985). Nerve tumours in the upper limb. A clinical review. Journal of Hand Surgery, 10B: 236-238. Johnson RJ, Bonfiglio M (1969). Lipofibromatous hamartoma of the median nerve. Journal of Bone and Joint Surgery, 51A: 984 990. Kehoe NJS, Reid RP, Semple JC (1995). Solitary benign peripheral nerve tumours. Review of 32 years' experience. Journal of Bone and Joint Surgery, 77B: 497-500. Mikhail IK (1964). Median nerve lipoma in the hand. Journal of Bone and Joint Surgery, 46B: 726-730.
Pulvertaft R G (1964). Unusual tumours of the median nerve. Report of two cases. Journal of Bone and Joint Surgery, 46B: 731-733. Rosenberg AE, Dick HM, Botte MJ. Benign and malignant tumours of peripheral nerve. In: Gelberman RH (Ed.): Operative nerve repair and reconstruction. Philadelphia, JB Lippineott, 1991, Vol. 2: 1587-1625. Seddon HJ. Surgical disorders of the peripheral nerves. Edinburgh, Churchill Livingstone, 1972. Stull MA, Moser RP, Kransdorf MJ, Bogumill GP, Nelson MA (1991). Magnetic resonance appearance of peripheral nerve sheath tumours. Skeletal Radiology, 20: 9-14. Yeoman PM (1964). Fatty infiltration of the median nerve. Journal of Bone and Joint Surgery, 46B: 737-739.
Received: 20 April 1996 Accepted: 4 July 1996 T. E .J. Hems, 24, Ashlong Road, Marston, Oxford OX3 0NH, UK. © 1997 The British Society for Surgery of the Hand