Mixed Bag for Tuesday, April 8th, 2025

Contributed by Children's Healthcare of Atlanta
Veronica Lopez, and Kiery Braithwaite.

History

A 10 month old male with no significant medical history presents to the pediatrician with chief complaint of fever, cough, bilateral conjunctivitis, and right neck swelling. The patient was started on Keflex for adenitis and developed a generalized rash, after which the antibiotic treatment was stopped. Respiratory panel resulted RSV+ and the patient was subsequently treated conservative.

The patient presents 3 weeks later for suspected leg pain noticed by mother, who reports resistance to diaper changes, decreased crawling and patient no longer standing up in his crib.

Blood work demonstrates mildly elevated ESR and CRP, otherwise labs values are within normal ranges. Right lower extremity radiographs are unremarkable. Hip ultrasound demonstrates trace bilateral hip joint effusions. MRI of the pelvis through the feet was obtained after patient was noticed to guard his left hip on physical exam.


Images (Click any image to enlarge)

Question

Which is the most likely etiology of the MRI findings?

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Correct answer

Kawasaki Disease

Discussion

Kawasaki disease is an inflammatory disease of small and medium-sized blood vessels mostly prevalent in the pediatric population. It's etiology remains unknown, however it is thought to be precipitated by an abnormal immune response to a toxin or infection. KD has a predilection to involve the coronary arteries, however there are several multisystem manifestations that result from the onset of a systemic vasculitis. Although more than half of patients with KD will meet clinical criteria, patients who present with atypical manifestations may require supplemental imaging as there is no pathognomonic test for KD diagnosis.

The following are the most common extracardiac manifestations of Kawasaki Disease:

Pulmonary: Peribronchovascular indistinctness (83%)

Gastrointestinal: Gallbladder hydrops (15%)

Genitourinary: Septic pyuria (Up to 80%)

Musculoskeletal: Arthritis (2-12.7%)

Neck: Cervical lymphadenopathy (42-75%)

CNS: Rare

It is important to be attune to these potential manifestations to facilitate timely diagnosis and appropriate treatment of patients who may present with atypical clinical features.

Differential diagnosis

  1. Multisystem Inflammatory Syndrome in Children (MIS-C) from SARS-CoV2/COVID-19
  2. Exanthematous Infection (bacterial or viral)
  3. Allergic or hypersensitivity reaction (drug reaction)
  4. Juvenile Idiopathic Arthritis


Additional images

References

  • Multisystem Imaging Manifestations of Kawasaki Disease Yuko Tsujioka, Atsuhiko Handa, Gen Nishimura, Masaru Miura, Koji Yokoyama, Kozo Sato, Hideo Handa, Masahiro Jinzaki, Shunsuke Nosaka, and Tatsuo Kono RadioGraphics 2022 42:1, 268-288