An adolescent with a history of complete Kawasaki disease presented with recurrent incomplete Kawasaki disease featuring acute-phase small-joint-predominant polyarthritis, which rapidly improved following intravenous immunoglobulin treatment without residual joint symptoms or coronary artery abnormalities.
Key Findings
Background
A patient with prior complete Kawasaki disease developed recurrent incomplete Kawasaki disease approximately a decade later.
The patient was an adolescent boy admitted on illness day 6.
He had been treated for complete Kawasaki disease approximately a decade earlier.
The recurrent episode met criteria for incomplete rather than complete Kawasaki disease.
This case documents recurrence of Kawasaki disease across a substantial time interval and across diagnostic categories (complete to incomplete).
Results
The acute phase of Kawasaki disease in this case was characterized by small-joint-predominant polyarthritis affecting the wrist and bilateral finger and toe interphalangeal joints.
The patient developed painful swelling of the left wrist and bilateral finger and toe interphalangeal joints.
Arthritis impaired grip strength.
Ultrasonography confirmed the presence of synovitis.
This pattern of small-joint involvement in the acute phase contrasts with the larger-joint arthritis more typically described in Kawasaki disease.
Results
Fever resolved by illness day 12, but arthritis persisted beyond fever resolution until after treatment.
Fever resolved by illness day 12.
Arthritis continued despite fever resolution.
Diagnosis of incomplete Kawasaki disease was made on illness day 18 following new conjunctival injection, lip erythema, and a secondary rise in C-reactive protein.
Intravenous immunoglobulin (IVIG) was administered after the illness day 18 diagnosis.
Results
Intravenous immunoglobulin treatment led to rapid improvement of arthritis with no residual joint symptoms or coronary artery abnormalities at discharge.
Arthritis rapidly improved following IVIG administration.
The patient was discharged without residual joint symptoms.
No coronary artery abnormalities were detected.
The prompt response to IVIG supported the diagnosis of Kawasaki disease over alternative diagnoses.
Results
The diagnosis of incomplete Kawasaki disease was triggered by a secondary rise in C-reactive protein alongside new conjunctival injection and lip erythema on illness day 18.
New conjunctival injection and lip erythema appeared on illness day 18.
A secondary rise in C-reactive protein was also observed at that time.
These findings collectively led to the diagnosis of incomplete Kawasaki disease.
The delayed recognition of incomplete KD highlights the diagnostic challenge of atypical presentations.
Discussion
Kawasaki disease-associated arthritis may vary by disease phase, with acute-phase polyarthritis sometimes involving small joints and later arthritis more typically affecting larger joints.
The authors note that 'KD-associated arthritis may vary by disease phase.'
'Acute-phase polyarthritis sometimes involving small joints and later arthritis affecting larger joints.'
This phase-dependent pattern of joint involvement is described as a distinguishing feature of KD-associated arthritis.
Awareness of this variation is highlighted as important for accurate diagnosis.
Discussion
Distinguishing acute-phase Kawasaki disease with small-joint arthritis from systemic juvenile idiopathic arthritis is clinically challenging and requires serial reassessment.
The authors state that 'distinguishing this presentation from systemic juvenile idiopathic arthritis can be challenging.'
'Serial reassessment of the clinical course and treatment response is essential.'
The overlap in clinical features between the two conditions contributes to diagnostic difficulty.
Treatment response to IVIG served as an important diagnostic clue in this case.
What This Means
This research describes a case report of an adolescent boy who developed Kawasaki disease (KD) for the second time, roughly a decade after his first episode. Kawasaki disease is an inflammatory condition that primarily affects children and can damage the blood vessels supplying the heart. In this recurrence, the disease presented in an incomplete form — meaning it did not show all the classic features — and was notable for causing painful swelling and inflammation in small joints, including the fingers, toes, and wrist. This is unusual because joint problems in Kawasaki disease are more commonly seen in larger joints. The diagnosis was further complicated because the fever resolved before the full picture of incomplete Kawasaki disease emerged, with the key diagnostic clues (eye redness, lip redness, and a rising inflammatory blood marker) only appearing nearly two weeks into the illness.
Once the diagnosis of incomplete Kawasaki disease was made and the patient was treated with intravenous immunoglobulin (IVIG) — the standard treatment for Kawasaki disease — the joint inflammation improved rapidly. The patient was discharged with no remaining joint symptoms and no heart artery damage, which is the most serious complication of Kawasaki disease. The authors note that the pattern of joint involvement in Kawasaki disease may differ depending on when in the illness it occurs, with smaller joints potentially affected early and larger joints later.
This case highlights two important challenges for clinicians: first, that Kawasaki disease can recur even years later; and second, that when it involves small-joint arthritis, it can be easily mistaken for another condition called systemic juvenile idiopathic arthritis. This research suggests that careful monitoring of how a patient's symptoms evolve over time — and how they respond to treatment — is essential for reaching the correct diagnosis, particularly when the presentation does not fit the typical picture of Kawasaki disease.
Suzuki K, Ishimaru S, Mihara Y, Kisohara S. (2026). Recurrent incomplete Kawasaki disease with small-joint-predominant arthritis during the acute phase.. BMJ case reports. https://doi.org/10.1136/bcr-2026-272465