Diagnostic journey of chronic eosinophilic pneumonia masked as lung cancer: a rare case report.

Introduction and Importance: Chronic eosinophilic pneumonia (CEP) is an idiopathic condition characterized by unusually high eosinophil infiltration in the lungs' interstitium and alveolar spaces. It is extremely rare, accounting for fewer than 3% of all interstitial lung diseases. CEP is frequently misdiagnosed as lung cancer, which can have catastrophic consequences for sufferers. When assessing patients with lung disease, doctors should be aware of CEP's symptoms and take its prognosis into account because it is a curable disorder. Case Presentation: A 40-year-old female presented in the outpatient department of gynecology with a history of abnormal vaginal bleeding for 3 months and mild shortness of breath without any other significant medical history or being under any medications. Physical examination findings were not significant. Clinical Discussion: Ultrasound revealed adenomyosis and a hysterectomy was planned. Chest radiograph revealed lung mass and computed tomography scan showed a well-defined mass with a pleural-based nodule. Histopathology revealed interstitial fibrosis and eosinophilic microabscesses. CEP was diagnosed and oral prednisolone was started with a 0.5 mg/kg/day dose. Chest radiographic abnormalities resolved after one month of treatment. Currently, she is asymptomatic. Conclusion: Early recognition and diagnosis of lung masses are essential for prompt treatment with corticosteroids. CEP can mimic lung malignancy and should be considered in patients with related symptoms.