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Huang, et al: Gout inflammation

Images in Rheumatology

Acute Gouty Inflammation of a Cystic TophaceousLesion of a Leg Muscle Associated with “Urate Milk”GUO-SHU HUANG, MD, Assistant Professor, Department of Radiology; DEH-MING CHANG, MD, Professor, Division of Rheumatology, Allergy, andImmunology, Department of Medicine; WEI-CHOU CHANG, MD; HUNG-WEN KAO, MD; YI-CHIH HSU, MD; CHENG-YU CHEN, MD, Professor,Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan. Address reprint requests to Dr. G-S. Huang, Department of Radiology, Tri-ServiceGeneral Hospital, 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan. E-mail: gsh5@seed.net.tw

The patient, a 44-year-old alcoholic man, presented withpainful swelling of the left leg for 2 weeks. He had a histo-ry of gout involving bilateral feet, ankles, and knees, withirregular treatment for 12 years. He reported no recent orremote history of a fall or trauma to his left calf. Physicalexamination showed regional swelling of the medioposteri-or aspect of the left leg with erythematous and warm skin.There was no subcutaneous tophaceous lesion or skin woundof his left leg. No evidence of subcutaneous or periarticularurate tophi at other sites was found. No fever was noted. Thelaboratory data revealed elevation of serum uric acid of 11.2

mg/dl (normal range 2.8–8.0 mg/dl). The white blood cellcount and serum creatinine level were within normal limits.Other laboratory data were noncontributory. At that time, aclinical diagnosis of cellulitis or pyomyositis or soft-tissuegout was made. For further evaluation of the extent of thelesion, magnetic resonance imaging (MRI) was performed.MRI showed a lobulated, cystic-like mass with septations inthe medial gastrocnemius muscle, with slightly high signalintensity relative to muscle on T1-weighted spin-echoimages (Figure 1A), and high signal intensity with internaldot-like or irregular low signal intensity on short-tau inver-

Figure 1. A. MRI shows a lobulated, cystic-like mass with septations in the medial gastrocnemius muscle, with slightly high signal intensity relative to mus-cle on T1-weighted spin-echo images. B. STIR image shows high signal intensity with internal dot-like or irregular low signal intensity. There is infiltrativeedema in the surrounding muscles and the overlying subcutaneous tissues.

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sion recovery (STIR) images (Figure 1B). There was infil-trative edema in the surrounding muscles and the overlyingsubcutaneous tissues on STIR images (Figure 1B). Becausethere was no communication between the cyst-like lesionand the knee joint and surrounding bursae, an unusual pres-entation of a Baker cyst with soft-tissue dissection or a rup-tured Baker cyst was excluded. Based on the MRI findings,the lesion was thought to be pyomyositis with abscess for-mation or intramuscular hematoma. Sonography of thelesion sowed a cystic mass in the medial gastrocnemiusmuscle. Sonography guided aspiration of the cystic lesionwas performed. Mixed milky and bloody fluid was aspirat-ed. Polarized light microscopy of the aspirated fluid showedneedle-shaped urate crystals with negative birefringence.Cultures for bacteria, tuberculosis, and fungus were all neg-ative. The final diagnosis was muscular gout. There was noconcomitant infection of the cystic tophaceous lesion. Thepatient received medication with regimens of colchicine andbenzbromarone, and the leg pain subsided. Symptoms sub-sided and the cystic lesion had disappeared on followupsonogram 3 months later, and there was no recurrence in a 3year followup.

Subcutaneous gout may be rarely complicated with sec-ondary infection and necrotizing fasciitis1, and the clinicalpresentation may initially resemble erysipelas or cellulitis.Tophaceous gout mimicking an abscess has been occasion-ally reported in the spine2. Acute gouty arthritis or bursitisassociated with “urate milk” has been occasionally report-ed3.

We have described the first case of acute gout of theperipheral muscle that presented with a cystic mass of “uratemilk”; in such a case, clinical presentation and MRI findingsmay mimic pyomyositis with abscess formation.

REFERENCES1. Yu KH, Ho HH, Chen JY, Luo SF. Gout complicated with

necrotizing fasciitis — report of 15 cases. Rheumatology Oxford2004;43:518-21.

2. Bonaldi VM, Duong H, Starr MR, Sarazin L, Richardson J.Tophaceous gout of the lumbar spine mimicking an epiduralabscess: MR features. AJNR Am J Neuroradiol 1996;17:1949-52.

3. Fam AG, Reis MD, Szalai JP. Acute gouty synovitis associated with“urate milk.” J Rheumatol 1997;24:2389-6.

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