Journal of Plastic, Reconstructive & Aesthetic Surgery (2010) 63, e788ee791

CASE REPORT

An unusual cause of carpal tunnel syndrome*

A.J. Robinson*, M. Haj Basheer, K. Herbert

Northern Ireland Plastics and Maxillofacial Service, Ward 10/11, Ulster Hospital, Dundonald, Northern Ireland

Received 5 December 2009; accepted 18 June 2010

KEYWORDSLipofibromatoushamartoma;Carpal Tunnelsyndrome;Magnetic Resonanceimaging

* This case has not been presented apart.* Corresponding author. 15 Rosepark

BT5 7RG. Tel. þ4428 90482235.E-mail address: arobinson13@hotm

1748-6815/$-seefrontmatterª2010Bridoi:10.1016/j.bjps.2010.06.019

Summary Most cases of carpal tunnel syndrome are idiopathic. One condition associatedwith carpal tunnel syndrome is a lipofibromatous hamartoma. We describe a case of a lipofibro-matous hamartoma presenting as a soft tissue wrist swelling with associated symptoms andsigns of carpal tunnel syndrome.

We advocate that all soft tissue swellings of the wrist with associated neurological signs beinvestigated appropriately, avoiding unnecessary additional surgery.ª 2010 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published byElsevier Ltd. All rights reserved.

Carpal tunnel syndrome is caused by compression of themedian nerve in the carpal tunnel. Most cases are idio-pathic. One condition associated with carpal tunnelsyndrome is lipofibromatous hamartoma.1 We report a caseof carpal tunnel syndrome caused by a lipofibromatoushamartoma and review the current literature concerning itsmanagement.

Case Report

A 38-year-old female complained of a 15-year history ofprogressive pins and needles and numbness affecting herleft hand. She described weakness of the hand and

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experienced difficulty performing daily tasks and droppingobjects. Examination revealed a soft non-fluctuant mass onthe volar aspect of her wrist, sensory loss in the distributionof the median nerve and weakness of the abductor pollicisbrevis and of opposition of her thumb. Phalen’s and Tinel’stests were both positive. Nerve conduction studies wereconsistent with carpal tunnel syndrome.

An operation carried out as part of a waiting list initia-tive to excise the lipoma and decompress the carpal tunnelwas abandoned after failure to separate the nerve from thelipomatous tissue.

Magnetic Resonance Imaging (MRI) after the first oper-ation confirmed a lesion of the median nerve suggestive ofa lipofibromatous hamartoma. (Figures 1 and 2)

A second operation confirmed the tumour to be unre-sectable, as the tumour was adherent to the nerve fasci-cles. Resection would have resulted in severe injury to thenerve. The abnormal tissue was biopsied.

The median nerve was sausage shaped, yellow anduniformly hypertrophied. It extended from the level of the

tiveandAestheticSurgeons.PublishedbyElsevierLtd.All rightsreserved.

Figure 1 Coronal T1 weighted MRI image of left wrist demonstrating hyperintense signal of the lipofibromatous hamartoma. Theimage demonstrates the characteristic spaghetti-like appearance of the fascicles. The lesion is compressed in the carpal tunnel.

An unusual cause of carpal tunnel syndrome e789

mid forearm to mid palm and extended into the terminalmotor and sensory branches of the median nerve (Figure 3).Decompression of the carpal tunnel was performed inaddition to release of the deep fascia of the forearm.Histopathology identified the lesion as a lipofibromatoushamartoma.

At review 2-weeks following surgery, the pins and nee-dles had resolved. The numbness remained. At her one-yearreview she reported occasional pain within her scar butotherwise she reported no pins and needles or numbness.Compared to the left side, she had slightly reduced oppo-sition of her thumb.

Discussion

A lipofibromatous hamartoma is a benign lesion that isslowly progressive.2 They are commonly present for many

Figure 2 Sagittal gradient T2 weighted MRI image of the left wcarpal tunnel and marked compression within the tunnel.

years before becoming symptomatic. These lesions occurmost commonly in children and adolescence, with themajority occurring before the 3rd decade.3

Lipofibromatous hamartomas occur three times morecommonly in the upper limb than the lower limb, mostcommonly affecting the median nerve.3,4 They have alsobeen reported to affect the ulnar, radial, plantar and suralnerves.3,4

Lipofibromatous hamartomas morphologically consistof fatty, fibrous and neural tissues within the nervesheath. Macroscopically they have the appearance ofa fleshy yellow mass compressing the median nerve withfibrofatty strands invading the perineurium.5 Micro-scopically, fibrofatty elements of the tumour arefrequently observed invading the perineurium andendoneurium separating the individual nerve fibres orgroups of fibres.5

rist demonstrating the expanded nerve proximal and distal to

Figure 3 Intra-operative picture of Lipofibromatous hamar-toma of the median nerve.

e790 A.J. Robinson et al.

Presentation

The most common complaint at presentation is of a slowlyexpanding, soft, non-tender mass on the volar aspect of thewrist or distal forearm.1 Associated clinical symptomsinclude pain and numbness, along with motor and sensorydeficits in the median nerve distribution. The symptoms andsigns of carpal tunnel syndrome arise from compression ofthe median nerve in the confines of the carpal tunnel or asa direct consequence of intraneural involvement leading toa compressive neuropathy. There are no physical signs thatdistinguish a lipofibromatous hamartoma from other wrist orhand pathology involving themedian nerve pre-operatively.3

These lesions are frequently diagnosed post-operatively.

Investigations

Pre-operative diagnosis can be confirmed by radiologicalinvestigations and neurophysiological studies. Ultrasoundshows longitudinally orientated alternating hypoechoic andhyperechoic bands. The hypoechoic bands represent theneural bundles and the hyperechoic bands represent thefat.6

MRI shows a unique and characteristic appearance. Fatappears bright on a T1 weighted image, whereas waterappears black. On a T2 weighted image fat appearshyperintense and water appears bright. On Gradient T2 (fatsuppression) fat appears similar (Isointense) to muscle.

T1 weighted images of these tumours present a ‘cable-like’ appearance of the infiltrating high-signal adiposetissue into the low signal nerve tissue.3 On coronal planesthey have a spaghetti-like appearance (Figure 1). Theserepresent thickened nerve fascicles, surrounded by evenlydistributed fat. On Gradient T2 weighted images lipoma-tous material appears isointense to muscle (Figure 2).These appearances on MRI are often diagnostic of a lip-ofibromatous hamartoma. MRI cannot delineate the degreeof fascicular involvement.7

Neurophysiological studies show reduced conductionvelocity, prolonged latency and decreased amplitude inkeeping with nerve compression.

Management

The main stay of treatment is conservative management.Tumour regression has been demonstrated with decompres-sion of the carpal tunnel and release of the overlying ante-brachial fascia of the forearm as demonstrated in our case.2,3

An incisional biopsy should be preformed to confirm thediagnosis. Release of fascia surrounding the median nerve issufficient to cause decrease in the size of themass, resolutionof symptoms and improvement in the strength of opponenspollicis.3 This is our policy to divide the flexor retinaculum,release the antebrachial fascia and to perform an incisionalbiopsy for histopathological confirmation of tumour type.

Surgical excision of a lipofibromatous hamartoma is notrecommended. Radical surgery involving interfasciculardissection is rarely indicated. Interfascicular dissectiondisrupts the segmental vascular supply from the epineuralvessels, which can lead to ischaemic complications.8 Therecovery is poor because the healing response createsa fibrotic wound bed interfering with nerve transmission andthe involved nerve fibres that are infiltrated by fibrofattytissues remain unchanged. Excision can result in permanentneurological change, both sensory and motor. Some of thesepatients suffer from intractable neuropathic pain.

Other approaches include microsurgical intraneuraldissection of the neoplastic elements, complete excision ofthe infiltrated nerve with or without nerve grafting,debulking of the fibrofatty sheath if macrodactyly ispresent or occasionally compensatory tendon transfer torestore hand function.7,8 Resection of the tumour in mostcases is impossible.

In summary, lipofibromatous hamartomas are rarebenign tumours affecting nerves. They commonly presentwith symptoms and signs of nerve compression. Thoseaffecting the median nerve present with carpal tunnelsyndrome. Release of the flexor retinaculum andsurrounding fascia is suffice to cause long term resolution ofsymptoms. Interfascicular dissection is rarely indicated.

Acknowledgements

We would to thank Dr Ronan McNally, Consultant Radiolo-gist for his help with preparation of the radiological imagesand the Department of Medical illustration for their helpwith the intra-operative pictures.

Conflict of interest

We have no conflicts of interest.

References

1. Houpt P, Storm van Leeuwen B, van den Bergen HA. Intraneurallipofibroma of the median nerve. J Hand Surg 1989;14A:706e9.

2. Chandler EM, Chen CM. Bilateral fibrolipoma of the mediannerve. JPRAS 2009;62:e99e100.

3. ElsaidiGA,Wiesler ER. Lipofibromatous hamartomaof themediannerve: case presentation of MRI, ultrasound, electrodiagnostic,histologic and surgical findings. Am J Orth 2004;33:514e6.

4. Razzaghi A, Anastakis DJ. Lipofibromatous hamartoma: reviewof early diagnosis and treatment. Cana J Surg 2005;48:394e9.

An unusual cause of carpal tunnel syndrome e791

5. Camilleri IG, Milner RH. Inreneural lipofibroma of the mediannerve. J of Hand Surg (Br) 1998;23:120e2.

6. Toms AP, Anastakis D, Bleakney RR, et al. Lipofibromatoushamartoma of the upper extremity: a review of the radiologicfindings for 15 patients. AJR 2006;186:805e11.

7. Bonneau LA, Delatte SJ, Bentz ML. Intraneural lipoma of theulnar nerve. Plast Reconstr Surg 2009;123:e40e1.

8. Kronberger P, Rainer C, Hittmair A, Anderl H. Lipofibromatoushamartoma (Neural Fibrolipoma) of a flexor nerve of the indexfinger. Scand J Plast Reconstr Hand Surg 1998;32:237e9.