A clinical conundrum: An unusual case of kawasaki disease in a boy with fever and unilateral axillary lymphadenopathy

ABSTRACT

Case Report A 7-year-old healthy boy with a history of COVID-19 infection 10 months ago and history of recent tick exposure presented with 6 days of intermittent fevers up to 40C and right sided axillary lymphadenopathy. During his first emergency room visit, labs were reportedly normal and the patient was discharged home. The next day, his fevers continued and he developed generalized abdominal pain and emesis. At his pediatrician's office, labs were significant for a leukocytosis. He then developed conjunctivitis and was admitted to an outside hospital for worsening fever and emesis. There, labs were significant for a C reactive protein (CRP) of 7.9 mg/dL and erythrocyte sedimentation rate (ESR) of 51 mm/hr. Urinalysis had no pyuria. Tick titers were also obtained. He was transferred to our facility for additional treatment with concern for Kawasaki disease due persistent fevers, cervical lymphadenopathy, lip redness, and a generalized rash. Upon arrival to our facility, he was well-appearing. Besides an intermittent rash with fevers, review of systems was otherwise negative. Our initial differential diagnosis included Kawasaki Disease, Multisystem inflammatory syndrome due to COVID-19 (MIS-C), tick-borne illness, or a systemic viral infection such as adenovirus. Examination was significant for conjunctivitis and small mobile right axillary adenopathy. Laboratory studies were significant for leukocytosis (15,000/mm3), elevated CRP (10.1 mg/dL), and elevated ESR (85 mm/hr). A respiratory viral panel and COVID-19 serology were both negative. D-dimer was elevated at 295 ng/mL. The rest of his labs including chemistries were normal. An echocardiogram was obtained, which was normal, and infectious disease was consulted. He was started on empiric doxycycline due to the history of tick exposure. He was observed overnight and developed no further fevers. However, due to his continued abnormal laboratory studies and in the setting of an otherwise negative workup for other diagnoses, we treated him for KD. He was started on high dose aspirin and given 2 g/kg of IVIG. 24 hours after completing IVIG, he had a fever of 38C, so he was observed an additional 24 hours. He was discharged home to complete a 7-day course of doxycycline and on low dose aspirin with plans to follow up with cardiology clinic. Our case makes many illustrative points for the clinician. Our patient had four of the five findings involving bilateral conjunctivitis, oral changes (strawberry tongue/injected pharynx/ fissured lips), peripheral extremity changes, polymorphous rash, and cervical lymphadenopathy. However, many of these symptoms were absent upon arrival to our facility and his fevers had subsided. There were also other factors such as his age that were unusual for typical KD along with his recent tick exposure and past COVID-19 infection that made his diagnosis more difficult to determine. This case highlights the importance of remebering that common conditions may have unusual presentations.