Dorsal Masses Over the MCP Joint

Initial Diagnostic Approach

The American College of Rheumatology recommends assessing functional impact on activities of daily living (ADLs) to determine treatment urgency and guide management decisions 3
The initial clinical evaluation should examine for joint effusion, synovial proliferation, or tendon involvement through physical examination of the dorsal MCP joint 1, 2
Ultrasound is the first-line imaging modality for evaluating dorsal hand masses, and can reliably detect ganglion cysts, synovial cysts, tendinitis or tenosynovitis of extensor tendons, and bony lesions 1, 2
A standard ultrasound scanning protocol should include dorsal longitudinal and transverse scans, as well as dynamic examination with active finger flexion/extension to evaluate tendon function 1, 2

Ganglion cysts are the most common soft tissue masses around the MCP joint, typically presenting as firm, non-tender masses that may fluctuate in size 1, 2, 4
Alternative diagnoses to consider include synovial cyst associated with underlying osteoarthritis or inflammatory arthritis 1, 2, rheumatoid nodule if patient has history of rheumatoid arthritis 1, 2, crystal deposition (gout or pseudogout) 1, 2, extensor tendon pathology including tenosynovitis or tendon sheath ganglion 1, 2, and bony prominence or osteophyte from degenerative changes 1, 2

Consider soft tissue sarcoma if the mass demonstrates rapid growth or size >5 cm, deep location relative to fascia, fixed to underlying structures, or associated pain or functional limitation disproportionate to size 4
If sarcoma is suspected, obtain core needle biopsy under image guidance before any attempted excision 4

Observation alone is appropriate for asymptomatic or minimally symptomatic masses, masses that do not interfere with hand function or ADLs, and confirmed ganglion cysts without associated pathology 1, 2, 3
Aspiration can be attempted for symptomatic ganglion cysts causing pain or functional impairment, with note that recurrence rates after aspiration are high (40-70%) 1, 4
Surgical removal is indicated when conservative management fails and symptoms persist, the mass significantly impairs hand function or ADLs, or there is diagnostic uncertainty requiring tissue diagnosis 3, 4

Provide joint protection education and assistive devices if the mass causes functional limitation 3
Consider splinting if there is associated joint instability or pain with use 3
Thermal modalities may provide symptomatic relief for associated pain or stiffness 3

Do not perform excisional biopsy without imaging if there is any concern for malignancy, as this can compromise definitive surgical margins 4
Do not assume all dorsal masses are benign ganglions—always obtain imaging to exclude other pathology 1, 2
Ensure proper positioning during ultrasound examination to avoid missing associated tendon or ligamentous pathology 1, 2