The hypereosinophilia dilemma: what's beyond cardiac involvement?

We present the longitudinal evolution of a previously published case of hypereosinophilic syndrome (HES) with cardiac involvement. A 27-year-old woman initially presented with eosinophilic myocarditis and peripheral neuropathy in the absence of a clear etiology, fulfilling criteria for idiopathic HES. Despite thorough investigations, eosinophilic granulomatosis with polyangiitis (EGPA) could not be confirmed due to the lack of clear criteria. The patient responded favorably to corticosteroids and heart failure treatment, with normalization of eosinophil count and improvement of left ventricular systolic function to near-normal parameters. However, during the following 1.5 years, she developed persistent asthma and subsequently presented with recurrent eosinophilia, severe fatigue, and systemic symptoms. This constellation now fulfilled the American College of Rheumatology and Lanham criteria for EGPA. Pulse therapy with intravenous methylprednisolone was initiated, followed by initiation of Rituximab (500 mg bid), and afterward maintained on a remission protocol consisting of Rituximab and gradual tapering. This protocol led to a clinical and biological improvement. Cardiac function remained unaffected. This updated case highlights the evolving nature of EGPA and reinforces the importance of long-term follow-up in patients with hypereosinophilia and cardiac involvement. Atypical presentations of disease underscore the importance of maintaining a high index of clinical suspicion, accompanied by diligent follow-ups, to ensure accurate and timely diagnosis. Early diagnosis and prompt initiation of therapy remain crucial for improving prognosis and preventing organ damage.