DOI:10.2214/AJR.06.0661
AJR 2006; 187:W658-W659
© American Roentgen Ray Society
MR Features of Vertebral Tophaceous Gout
Jason Oaks,
Steven D. Quarfordt and
James K. Metcalfe
University of Tennessee College of Medicine Chattanooga, TN
37403
WEB—This is a Web exclusive article.
Keywords: arthritis • metabolic disorder • vertebral tophaceous gout
Gout is a common metabolic disorder affecting approximately 1.4% of the
population [1]. The prevalence
is three times higher in men than women and usually involves the middle aged
and elderly (30-70 years). Gout causes acute arthritis due to the accumulation
of monosodium urate crystals. It usually involves the extremities, with rare
involvement of the spine
[2].
A 32-year-old man with a recent diagnosis of gout presented for evaluation
of back pain and progressive lower extremity paresthesias. At physical
examination, findings were diminished light touch and vibratory sensation to
both lower extremities. Diminished reflexes were also noted.
Multiplanar fast spin-echo MRI was performed before and after contrast
administration (20 mL of gadoversetamide). A large heterogeneous mass (6.5
x 4 x 2.5 cm) was found along the posterior portion of T5-T8, with
involvement of the neural arch and extension into the posterior lamina.
T2-weighted images depicted mixed areas of low and intermediate signal
intensity. Sagittal and transaxial images showed an area of low signal
intensity with compression of the thecal sac (Figs.
1A and
1B). Increased signal was seen
within the central thoracic cord at the level of T7-T8, indicating possible
spinal cord injury. T1-weighted images showed areas of mostly intermediate
signal intensity with some areas of low intensity
(Fig. 1C). Heterogeneous
enhancement was noted on contrast-enhanced images
(Fig. 1D).
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Fig. 1A —32-year-old man with vertebral tophaceous gout. Sagittal
T2-weighted image shows mass with mixed areas of low to high signal intensity.
Compression of thecal sac with increased signal in central cord is noted.
|
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Laminectomy and excision of the mass were performed, and tissue was
submitted for pathologic analysis. Preparation of the tissue revealed numerous
needlelike crystals that were noted on polarized microscopy. Polarization with
a red compensator showed uric acid crystals of superimposed calcium
pyrophosphate crystals, both of which are consistent with a diagnosis of
gout.
Gout rarely involves the axial skeleton. According to published reports,
vertebral gout predominantly affects men ranging in age from 33 to 76 years.
Clinical presentation varies from back pain to neurologic symptoms
[2].
MRI of gout has been described; however, data are limited for vertebral
gout. T1-weighted imaging of gout depicts tophi that routinely appear to have
low to intermediate signal intensity. T2-weighted imaging is more variable;
lesions with signal intensities ranging from low to high have been described
[3].
The variable appearance of spinal gout on T2-weighted imaging is a
described finding. It has been postulated that high signal intensity found in
some tophi corresponds with high protein content that is often found in the
center of the tophus. Other authors have suggested that the high signal
intensity is a result of local increases in the water content of the tophus.
The low signal intensity that is noted on T2-weighted images may be the result
of regions of calcification that is commonly found within gouty tophi
[4].
Enhancement patterns of gout have also been examined and are variable. Both
homogeneous and heterogeneous enhancement patterns are found and are thought
to be related to differences in the relative amounts of vascular fibrous
tissue found within the tophus itself
[4,
5].
Spinal involvement of gout is an exceedingly rare finding. The differential
diagnosis for vertebral masses that have a variable appearance on MRI should
include gout, especially in patients with a known history of hyperuricemia.
Tissue is required for the definitive diagnosis, but is not always necessary
if clinical and radiographic findings provide a reasonably high suspicion for
gout.
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