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Case of the Week - Patient Summary 7075
Peer Reviewed and Certified -

Approved by: Donald J Flemming -

Demographics: 77 y.o. man

History & Chief complaint:

77 year old with "cyst on finger".

Physical exam and Laboratory:

WBC: 7.7 K/uL
Cholesterol: 125 mg/dL
Uric Acid: 4.2

Gram Stain:
NO WHITE BLOOD CELLS OR ORGANISMS NOTED.

SYNOVIAL FLUID - Birefringent crystals . . . . . . . URATES

SYNOVIAL FLUID - Bacteriology Result:
NO GROWTH AFTER 5 DAYS

Summary of Findings:

AP, lateral and oblique views of the left third digit demonstrate a soft tissue mass on the extensor surface of the PIP joint. There is mild erosive change of the radial aspect of the proximal phalangeal head with preservation of joint space and normal mineralization.

Differential Diagnosis:

Soft tissue mass without calcification (DDX):
Amyloidosis
Xanthomatosis
Psoriasis
Tophaceous Gout

Diagnosis:

Tophaceous Gout

Confirmed by: Aspiration of cystic contents, which demonstrated birefringent crystals in synovial fluid.

Treatment and Followup:

Patient is currently undergoing workup from orthopedics.

Patient Specific Discussion: (Also Read the Disease Discussion)

This patient with no known history of gout presented with a cystic lesion by physical exam. The nonspecific soft tissue swelling with erosion in the head of the proximal phalanx still included a broad differential. Tissue diagnosis confirmed the etiology.

Xanthomatosis occurs on the extensor surfaces of limbs with associated erosions. History of hypercholesterolemia and tissue aspirate differentiates this disease.

Psoriasis presents with soft tissue swelling with normal bone density and articular erosion. Hyperuricemia can occur in psoriasis secondary to rapid cell turnover.

Amyloidosis presents with soft tissue swelling and erosions. This is typically symmetric and is associated with juxtaarticular osteopenia.

Disease Discussion - Tophaceous Gout

Tophaceous gout manifests in patients with established disease. It involves deposition of urate, protein matrix, inflammatory cells and giant cells in soft tissues. The deposits can occur in tendons, ligaments, cartilage, bone and other soft tissue. There is a tendency for deposits to occur in the following areas: olecranon bursa and cartilage of the ear, nose and menisci. Osteolysis may occur with soft tissue deposits. Nodules contain monosodium urate crystals. The subcutaneous tophaceous deposits may be the initial manifestation of gout. Gout nodulosis describes a subset of patients without arthritis who develop tophi in soft tissues.

The common locations in the hand and wrist include the following in order of decreasing frequency: DIP joints, IP joints and MCP joints.

Case and/or Image Source: Rick Riego de Dios
Submitted by: Rick Riego de Dios -

Affiliation: National Capital Consortium

Approved By: Donald J Flemming -

Affiliation: Penn State University

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