January 10, 2022/Pediatrics

Maintain a Broad Differential When Diagnosing Arthritis in Children

Patient with intermittent pain and swelling in knee initially appears to have juvenile idiopathic arthritis


A 15-year-old male presented with right knee pain and swelling that had been intermittent for ten years.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Upon exam, juvenile idiopathic arthritis (JIA) appeared to be a preliminary diagnosis, although his symptoms were not emblematic of chronic arthritis. The swelling was episodic, occurring only every few months, and typically only lasting less than a week. After that, his knee felt completely normal.

An ultrasound confirmed arthritis in his right knee, but he had no fever or other positive findings for JIA. An X-ray and lab studies, which included: a complete blood count, inflammatory marker test, gonorrhea culture, Lyme disease, rheumatoid factor, cyclic citrullinated peptide antibodies and HLA-B27 tests were all normal. Additionally, the duration of pain and swelling did not support an infectious cause, and he was otherwise healthy without systemic rheumatologic conditions.

Joint aspiration was completed in clinic, allowing the team to retrieve serosanguinous fluid from the joint and inject a steroid.

The patient returned six months later with another episode of pain and swelling in his right knee. This time, the bedside ultrasound revealed an increase in Doppler signal within the Hoffa fat pad, which is not a typical site for synovitis JIA.


MRI confirms new diagnosis: synovial hemangioma

The team proceeded with an MRI, which revealed a 4 cm mass within the Hoffa’s fat pad. The mass was multilocular with hyperintensity, consistent with synovial hemangioma, a rare benign tumor. He was referred to the Department of Orthopaedics, where the team led an arthroscopic excision of the mass and synovectomy.

The diagnosis, confirmed on histopathology, explained the off-and-on knee swelling was caused by episodic intraarticular bleeding and hemosiderotic synovitis.


What is the lesson?

In this case, JIA was a diagnosis of exclusion. When it comes to arthritis in children, maintain a broad differential of potential etiologies.

Related Articles

Young patient with endoscopy device
April 17, 2024/Pediatrics/Cardiology
Cleveland Clinic Plays Many Roles in Developing Pediatric-Specific Devices

Programs bring age- and size-appropriate technology to children

Little boy with cancer sitting in chair
April 11, 2024/Pediatrics
Outcomes in Hodgkin Lymphoma Are Improving, but Disparities Persist

Unpacking advancements and identifying drivers of inequity

Child rubbing her aching head
Innovations in Pediatric Pain Rehabilitation

Self-efficacy mindset, burst therapy and increased biofeedback may help improve outcomes

Teen patient sitting in exam room with gastroenterologist
EoE Transition Clinic Drives Continuity of Care

Pediatric and adult gastroenterologists offer team care for patients with eosinophilic esophagitis

Patient in hospital getting bone marrow transplant
Updated Recommendations for Long-Term Survivors of Bone Marrow Transplant

New guidelines expand on psychosocial, sexual health, cognitive and other issues

Closeup of bone marrow
Bridging the Gap Between Bone Marrow Transplant and cGvHD

Consensus conference begins work on new recommendations for clinical care and research

Woman in chair breastfeeding an infant
March 15, 2024/Pediatrics/Primary Care
Breastfeeding Duration in U.S. Closely Linked With Length of Maternity Leave

Systemic change needed to improve health outcomes for parents and children, say researchers

Illustration of a liver
Case Study: Late Diagnosis of Glycogen Storage Disease

Rare genetic variant protected siblings against seizures and severe hypoglycemia