Acute exacerbation of idiopathic hypereosinophilic syndrome following asymptomatic coronavirus disease 2019: a case report

BACKGROUND: Previous research has suggested that some autoimmune diseases develop after the occurrence of coronavirus disease 2019. Hypereosinophilic syndrome is a rare disease presenting with idiopathic eosinophilia and multiple organ involvement, including the skin, lungs, gastrointestinal tract, heart, and nervous system. The diagnosis of idiopathic hypereosinophilic syndrome poses a dilemma because clinical manifestation and serum biomarkers are similar to those of eosinophilic granulomatosis with polyangiitis. Only a few cases have been reported where coronavirus disease 2019 may have caused the new onset or exacerbation of eosinophilic granulomatosis with polyangiitis or idiopathic hypereosinophilic syndrome. CASE PRESENTATION: We present the case of a 48-year-old Japanese woman with history of asthma who developed deteriorating symptoms of insidiously developed idiopathic hypereosinophilic syndrome following asymptomatic coronavirus disease 2019. She developed acute-onset back pain, tachycardia, abdominal discomfort, loss of appetite, weight loss, skin rash on the back, and numbness of the extremities 3 days after the quarantine period. Extreme hypereosinophilia with multiple abnormal findings including pulmonary ground-glass opacity lesions and mononeuritis multiplex was consistent with hypereosinophilic syndrome. Normal cellularity with eosinophilic proliferation in the bone marrow and negative FIP1L1–PDGFRA raised the diagnosis of idiopathic hypereosinophilic syndrome. Although the patient tested negative for anti-neutrophilic cytoplasmic antibodies and skin biopsy was negative for vasculitis, eosinophilic granulomatosis with polyangiitis could not be excluded. Since glucocorticoids are a standard therapy for both idiopathic hypereosinophilic syndrome and eosinophilic granulomatosis with polyangiitis, we initiated glucocorticoids following a multidisciplinary discussion. CONCLUSION: Although the relationship between asymptomatic coronavirus disease 2019 and acute idiopathic hypereosinophilic syndrome exacerbation was uncertain, the chronological order of the symptomatic development suggested a possible link. More clinical cases and population-based studies are needed to determine the potential effect of coronavirus disease 2019 on autoimmune diseases.