Can lymphoma (lymphatic system cancer) present as lumps in the joints?

Can Lymphoma Present as Lumps in the Joints?

Yes, lymphoma can present as lumps in or around joints, though this is an uncommon manifestation that often mimics inflammatory arthritis and requires a high index of suspicion for diagnosis. 1, 2

Primary Joint Involvement

Lymphoma can directly involve joints through synovial infiltration, presenting as:

• Monoarticular or polyarticular swelling that mimics rheumatoid arthritis or other inflammatory arthropathies 2
• Soft tissue masses around joints, particularly the sternoclavicular joint, with associated pain and swelling 1
• Para-osseous soft tissue swelling adjacent to joints that may be palpable as lumps 1

The sternoclavicular joint appears particularly vulnerable to lymphomatous involvement in reported cases. 1

Musculoskeletal Presentations

Beyond direct joint involvement, lymphoma commonly affects the broader musculoskeletal system:

• Subcutaneous nodules that can occur near joints, particularly in subcutaneous panniculitis-like T-cell lymphoma, which presents as solitary or multiple subcutaneous nodules with a characteristic "bruise-like" appearance 3, 4
• Primary cutaneous diffuse large B-cell lymphoma (leg type) manifests as red to bluish-red tumors on the legs in elderly patients, which could be mistaken for joint-related masses 3, 4
• Muscle involvement occurs in approximately 1.1% of non-Hodgkin lymphoma cases and can present as soft tissue masses that mimic sarcomas 5

Critical Diagnostic Features

The key distinguishing feature is bone destruction on imaging—radiographic evidence of associated bone destruction is the best indicator of lymphomatous arthropathy in patients presenting with rheumatic symptoms. 2

Additional red flags include:

• Monoarthritis with spontaneous fracture in the absence of significant trauma 1
• Lack of response to standard anti-inflammatory therapy, including glucocorticoids 1
• Absence of classic "B symptoms" (fever, night sweats, weight loss) does not exclude the diagnosis, as joint-presenting lymphoma often lacks systemic symptoms initially 1, 2
• Disproportionate soft tissue swelling relative to the degree of joint inflammation 1

Diagnostic Approach

When lymphoma involving joints is suspected:

1. Obtain MRI to evaluate para-osseous soft tissue involvement and bone marrow signal changes 1
2. Perform tissue biopsy (core needle or open biopsy) of the soft tissue mass or synovium—this is mandatory for definitive diagnosis 1, 2
3. Request immunophenotyping on biopsy specimens, looking for markers such as CD20+, CD79a+, BCL2+, BCL6+ in B-cell lymphomas 3, 4
4. Complete staging workup including CT scans and/or PET-CT to evaluate disease extent 6

Common Pitfalls

• Misdiagnosis as rheumatoid arthritis flare is the most common error, particularly in patients with pre-existing RA who develop new monoarticular symptoms 1
• Assuming inflammatory arthritis when a patient presents with joint swelling and pain without obtaining tissue diagnosis when symptoms are atypical or refractory to treatment 2
• Overlooking the diagnosis in patients without lymphadenopathy or hepatosplenomegaly, as joint-presenting lymphoma frequently lacks these classic findings 2
• Delaying biopsy in favor of empiric anti-inflammatory treatment when imaging shows bone destruction or disproportionate soft tissue involvement 1, 2

Clinical Context

In pediatric populations, joint or extremity pain may be the only presenting symptom of acute lymphoblastic leukemia, emphasizing that hematologic malignancies should always be in the differential for unexplained musculoskeletal complaints. 3

The immunophenotype varies by lymphoma subtype: diffuse large B-cell lymphoma typically shows CD20+, CD79a+, BCL2+, BCL6+, MUM-1+, FoxP1+ 3, 4, while subcutaneous panniculitis-like T-cell lymphoma demonstrates CD3+, CD4–, CD8+, with cytotoxic proteins 3