Case Report: Eosinophilic Myocarditis as a Paraneoplastic Syndrome in Classical Hodgkin’s Lymphoma

Introduction Eosinophilic myocarditis is a rare and aggressive form of infiltrative cardiomyopathy associated with significant morbidity and mortality, especially when diagnosis is delayed. Symptoms are often vague and overlap with other cardiac conditions, making recognition challenging. Positron emission tomography combined with computed tomography has become more relevant as a supplementary diagnostic tool, although its effectiveness in follow-up remains underexplored. This report discusses a likely paraneoplastic case in classical Hodgkin’s lymphoma, emphasizing that metabolic cardiac activity on serial imaging closely mirrored clinical progression. Case Presentation A 75-year-old woman with classical Hodgkin’s lymphoma initially responded well to chemotherapy and maintained stability for over eighteen months. She later developed progressive heart failure with restrictive physiology, biventricular involvement, severe pulmonary hypertension, and an apical intraventricular thrombus. Laboratory tests indicated intermittent eosinophilia and varying inflammatory markers. Multimodal imaging revealed diffuse myocardial edema and extensive endocardial fibrosis, indicating eosinophilic involvement. Across five oncological scans, myocardial metabolic activity increased alongside the patient's deterioration. Despite thorough investigations, including biopsies and ruling out infectious, autoimmune, infiltrative, and coronary causes, histological confirmation remained elusive. Given her advanced cardiac condition, comorbidities, and complications from treatment, immunosuppression and invasive interventions were not viable options, and the patient continued to decline. Conclusion This case illustrates the diagnostic challenges of eosinophilic myocarditis in unusual paraneoplastic contexts and underscores the value of multimodal imaging and interdisciplinary collaboration. The metabolic changes observed across sequential scans support this approach for early detection and follow-up, though additional validation is required.