DOI:10.2214/AJR.05.0336
AJR 2006; 187:W313-W315
© American Roentgen Ray Society
Chronic Tophaceous Gout of the Third Flexor Digitorum Profundus Tendon in the Hand: An Unusual Sonography Diagnosis
Peter R. Coombs1,
Nicholas Houseman2 and
Rohan White3
1 Department of Medical Imaging and Radiation Sciences, Clayton Campus, Monash
University, Blackburn Rd, Clayton, Australia 3800.
2 Department of Plastic and Reconstructive Surgery, The Northern Hospital,
Melbourne, Australia
3 Department of Medical Imaging, The Epworth Hospital, Melbourne,
Australia.
Received February 26, 2005;
accepted after revision April 11, 2005.
Address correspondence to P. R. Coombs
(Peter.Coombs{at}med.monash.edu.au).
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Keywords: dynamic sonography • gout • hand • musculoskeletal imaging • tophaceous gout
Introduction
Tophaceous gout in a flexor tendon of the hand is a rare form of
tenosynovitis. We report on a patient who presented with chronic swelling and
restricted movement of his left middle finger. Sonography displayed features
atypical of tenosynovitis. The enlarged tendon's normal fibrillar pattern was
replaced by increased echogenicity and heterogeneity. The tendon was highly
attenuative to transmitted sound. Subsequent surgery and histology confirmed
the diagnosis of tophaceous gout.
Case Report
A 63-year-old man presented after having developed a gradual inability to
flex his left middle finger during the previous 12 months. He had no known
history of gout. Physical examination revealed mild soft-tissue swelling of
the distal half of the finger. No associated soft-tissue erythema or crepitus
was seen. Posteroanterior, oblique, and lateral radiographs showed mild
osteopenia and soft-tissue swelling over the volar aspect of the finger
(Fig. 1A). No soft-tissue
calcification was shown.
The patient was referred for sonography to establish the integrity of the
tendon and to assess tendon movement. Dynamic sonography was performed with
the Antares imaging system (Siemens Medical Solutions) with a 12.5-MHz
transducer. A large amount of gel was used to obviate a standoff. Sagittal and
transverse planes were used to show the key features of the pathology.
Adjacent digits and the contralateral side were used for a normal comparison.
A SieScape imaging system (Siemens Medical Solutions) was used to show a long
length of tendon to clearly document the normal and abnormal parts of the
tendon in the same image.
Sonography showed abnormalities in the flexor digitorum profundus and the
flexor digitorum superficialis from their insertions to 4-mm proximal to the
proximal interphalangeal (PIP) joint. The distinctive features were markedly
increased echogenicity and heterogeneity in the tendon (Figs.
1B,
1C, and
1D). Posterior to the increased
echogenicity was loss of detail and shadowing indicating the tendon was highly
attenuating. The tendon was also slightly increased in size. Color Doppler
sonography showed no vascular pattern in the tendon. There was no fluid in the
synovial sheath apart from a small, unrelated 4-mm synovial cyst at the level
of the PIP joint. Visualization of the volar aspect of the distal and proximal
interphalangeal joints with sonography was significantly limited due to the
attenuating tendon. A 3-mm soft-tissue nodule was noted on the lateral aspect
of the finger, which was slightly hypoechoic when compared with the adjacent
soft-tissue (Fig. 1E). The
sonography diagnosis at the time of the examination was an atypical
presentation of tenosynovitis.
The patient was treated with oral nonsteroidal antiinflammatory medication.
This conservative management did not provide clinical improvement. Seven
months after the sonography examination, the patient underwent an exploration,
tenosynovectomy, and release of the A1 pulley. Observation at surgery showed
chalky, crystalline deposits on the surface tendon. Biopsy was performed.
Histopathology showed fragmented nodules with amorphous basophilic material
resembling sodium urate deposits surrounded by palisaded layers of histiocytes
and occasional multinucleate giant cells. These appearances are typical of
gouty tophus. Microscopy examination and subsequent culture did not reveal any
bacterial infection. Consistent with gout, uric acid crystals were detected by
polarizing microscopy, and an elevated serum uric acid of 0.60 mmol/L (normal
range is 0.12-0.45) was found on blood analysis.
Three months later, the patient returned to the operating theater because
of continued pain and active tenosynovitis. He then had further release of the
scarred A1 pulley and tenosynovectomy. The articular symptoms improved after
the surgery to his tendon and he is receiving aggressive physical therapy.
Discussion
Gout presents as the deposition of sodium urate crystals in joints,
tendons, nerves, or kidneys when production exceeds the excretion
[1]. Typically this is seen as
a peripheral arthritis. Extraarticular gout is less common, presenting as
nerve entrapment dermatitis, skin ulceration, sinus, or peritendinous nodular
change [2].
Sonography is a useful tool to evaluate gout in an equivocal clinical
setting to exclude alternative differential diagnoses. In an affected joint,
sonography may show joint widening, thickened periarticular tissues, and power
Doppler signal [3]. Effusions
and synovial thickening that are present in the other forms of arthritis may
be seen. Gouty synovial fluid tends to have a "snowstorm"
appearance with multiple heterogeneous foci
[4]. Tophi may be echogenic,
hypoechoic, or calcific. Cortical bony erosions may be seen adjacent to these
tophi [5].
Tenosynovitis is a highly unusual form of extraarticular gout. Eight cases
have been reported in the literature involving the distal flexor tendons of
the hand [1,
2,
6,
7]. Weniger et al.
[1] report three cases imaged
on MRI. Aslam et al. [8]
describe the only case that used sonography. In contrast, their case was an
acute presentation in which the tendon was normal but there was a loculated
collection of synovial fluid in the tendon sheath at the level of the A1
pulley [8].
The differential diagnosis in this case was synovitis, tenosynovitis, or a
partial-thickness tear of the tendon, although there had been no trauma.
Synovitis is seen on sonography as hypoechoic thickening of the synovial
sheath. Anechoic fluid may also be identified
[9]. Inflammatory changes to
the tendon produce areas of hypoechogenicity, loss of the fibrillary pattern,
and tendon enlargement [9,
10]. Power Doppler sonography
may show increased flow depicting inflamed synovium
[9]. In cases where there has
been a definite injury or repetitive movement, anechoic change and the
separation of fibers may reflect a tear to the tendon.
In this chronic case of gouty tenosynovitis, the tendon changes on
sonography were distinctly different from typical presentations. The flexor
digitorum tendons were slightly enlarged with a loss of normal fibrillar
pattern; however, increased echogenicity, marked heterogeneity, and
attenuation of the transmitted sound were seen. No other forms of
tenosynovitis have been reported in the literature with this distinctive
appearance. This case affirms the value of sonography in tendon imaging and
provides a primary differential diagnosis when these very distinctive
sonographic appearances are present.
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Introduction
Case Report
