Case of invasive mucinous adenocarcinoma mimicking chronic eosinophilic pneumonia

Invasive mucinous carcinoma is difficult to distinguish from other lung diseases; therefore, confirmation of the diagnosis may be delayed. A 64-year-old woman was admitted with a six-month history of cough, febrile sensation, and shortness of breath, with worsening symptoms. A computed tomography scan of the chest revealed bilateral homogenous ground-glass opacities and consolidation with subpleural predominance. The percentage of eosinophils in the serum and induced sputum was elevated and a diagnosis of chronic eosinophilic pneumonia was established. Despite administration of a systemic steroid, she did not rapidly respond. We performed a percutaneous needle biopsy and finally confirmed invasive mucinous adenocarcinoma.