HSS Ultrasound of the Month Case 109

Clinical History A 76 year old male presents with left knee pain and swelling.

On exam, the left knee was warm and swollen with several apparent small fluid filled cystic areas overlying the patella, without associated erythema.

Clinical concern was for pre-patellar bursitis.

Ultrasound-guided pre-patellar bursal aspiration and subsequent cortisone injection were requested.

Ultrasound of the Month – Case 109

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Ultrasound of the Month – Case 109

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Ultrasound of the Month – Case 109

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Diagnosis: Pre-patellar Gouty Tophus Treatment Subsequent ultrasound guided steroid injection into the pre-patellar nodule/collection was then performed.

Discussion • •

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Epidemiology: Males over the age of 40 Etiology: Hyperuricemia resulting in the deposition of monosodium urate crystals in and around joints – Often associated with excessive meat and alcohol intake Acute gouty flare: Painful, red, swollen joint, most characteristically involving the first metatarsophalangeal joint Chronic gout: Tophaceous collections of solid urate crystals about joints and bursae with associated destructive changes Treatment: – Acute: NSAIDs, colchicine, steroids, cytokine blocking agents – Chronic: Xanthine oxidase inhibitors, uricosuric drugs

Ultrasound of the Month – Case 109

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Discussion continued •

Imaging Findings: – Radiography: • • • •

Eccentric punched out “rat bite” erosions with sclerotic margins and overhanging edges Hyperdense tophaceous nodules with or without calcification Maintenance of the joint space until late in the disease Olecranon and prepatellar bursitis

– Ultrasonography: • • • •

Heterogeneous hyperechoic synovitis Erosions Superficial irregular hyperechoic crystal deposition along hyaline cartilage Heterogeneous hyperechoic tophi with anechoic rims

– CT: •

Dual-energy CT allows for detection of monosodium urate crystals, as well as for assessment of their amount and distribution

– MRI: •

Gouty tophi demonstrate intermediate or low T1 intensity, variable T2 intensity and homogeneous contrast enhancement

Ultrasound of the Month – Case 109

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