Article Text
Summary
A 79-year-old Caucasian woman with rheumatoid arthritis (RA) for 27 years presented with a swelling on her left wrist. Both pain and a tingling sensation in the radial four fingers could be elicited by applying light pressure on the swelling. The patient was uncertain as to the actual onset of this swelling and had not complained, as it resembled many of the swellings of the hand region she had previously experienced. Primarily, an organised tenosynovitis was suspected with a presumed pressure on the median nerve, and a puncture was considered. Ultrasonography diagnosed a large hypoechoic mass. This is not unusual with longstanding inflammatory changes, which may contain elements of connective tissue. Using the Doppler function it turned out to be highly vascularised. The tumour could not be removed, but histology revealed a diagnosis of schwannoma.
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Background
Ultrasound has been used for decades in many medical subspecialities and increasingly over the last few years in rheumatology.1 Even so, a clinical swelling will often be treated without further diagnostic procedures to save time. However, this non-invasive, dynamic examination method is cheap and may be applied immediately in the outpatients’ clinic. Ultrasound is not as costly as magnetic resonance imaging (MRI). In rheumatoid arthritis, the ordinary grey scale examination should be supplemented with Doppler imaging, enabling the examiner to detect synovial inflammation by arterial as well as venous blood flow. The current equipment is highly sensitive to such flow, which may be demonstrated even in small vessels.2,3
Case presentation
A 79-year-old Caucasian woman with severe and active rheumatoid arthritis for 27 years presented with a swelling on her left wrist. The patient had been aware of the swelling for several years, but it had not been recognised by the clinicians, who may have been somewhat cursory in their joint assessment of this longstanding disease. The patient had severe arthritis of the hands and a very weak handgrip. She therefore was relatively content with the swelling on which she rested her glass while drinking.
On examination, paresthesia of the four radial fingers was found under light pressure.
Primarily, a tenosynovitis pressing on the median nerve was suspected (fig 1). A puncture before injection of glucocorticosteroid was considered, guided by ultrasound.
Clinical photographs of the left wrist of a 79-year-old woman with rheumatoid arthritis.
Investigations
Ultrasound revealed a large hypoechoic mass. Using the Doppler function it turned out to be highly vascularised (fig 2). Spectral Doppler showed no signs of inflammatory flow—that is, no diastolic component of the flow.4 Accordingly, a non-inflammatory disease was suspected. A supplementary MRI diagnosed a neurinoma. During the subsequent operation, it was impossible to remove the tumour as the function of the patient’s hand was at risk. Apart from a biopsy it was left untouched and histology revealed the tumour to be a schwannoma.
Grey scale and colour Doppler ultrasonography (Acuson Sequoia, Mountainview, California, USA) of the tumour.
Differential diagnosis
Swellings of the hand are predominantly tenosynovitis, while tumours are to be excluded. Schwannoma of the hand and wrist are easily mistaken for a ganglion because they are well encapsulated and occasionally exhibit cystic changes.
A list of possible differential diagnoses and their clinical pictures is given in the table 1. Most of the suspected diagnoses must be confirmed by biopsy.
Difference diagnoses and clinical characteristics
Treatment
The treatment of choice is complete excision of the schwannoma as the nerve fibres are displaced and do not enervate the tumour.5 During surgical excision, careful dissection after longitudinal incision of the epineuria and avoidance of nerve retraction are vital so as to avoid neurological deficits
Outcome and follow-up
In this case, no treatment was possible. The patient died from other causes.
Discussion
The diagnosis of schwannoma in an uncommon region such as the hand remains one of difficulty.6 In the overlooked schwannoma presented here, the years of recurrent swelling due to arthritis and tenosynovitis had led to a certain acceptance by the patient and presumably also several of the treating doctors to such manifestations in the region of the wrist. This may explain why the tumour went unnoticed for several years, even though this tumour was among the very large schwannomas reported in the literature.7
The most common differential diagnoses in rheumatoid arthritis as mentioned in table 1 are tenosynovitis, joint inflammation and ganglion, which may all be diagnosed—and treated—with ultrasound guided techniques.8
Schwannomas are seldomly found in the peripheral nerves, while they may be situated in any nerve, including the ulnar and median nerves. The most common differential diagnoses in rheumatoid arthritis (table 1) are tenosynovitis, joint inflammation and ganglion, which may all be treated with ultrasound guided techniques.9 The National University Hospital of Copenhagen has records of 27 such cases over the past 10 years (unpublished data), which have all—except in the case presented here—been enucleated successfully by hand surgery. Our case of schwannoma of the median nerve in a patient with rheumatoid arthritis underlines the importance of joint examination at regular intervals, even in longstanding disease.
Learning points
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Examinations of joints in arthritis should be performed at regular intervals.
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Tendons and tendon sheaths should also be examined.
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A tumour must be diagnosed with the best available methods.
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Doppler analysis adds significant information to grey scale ultrasound.
Acknowledgments
The study was supported by the Oak Foundation
Footnotes
Competing interests: None.
Patient consent: Patient/guardian consent was obtained for publication.