A rare case of pulmonary lepidic metastasis in patient with branch-type intraductal papillary mucinous carcinoma of the pancreas.

Pulmonary lepidic metastasis from intraductal papillary mucinous carcinoma (IPMC) of the pancreas is extremely rare. The patient was a 50s-year old male who was hospitalized in the department of respiratory in our hospital for the evaluation of ground-glass opacities in both lungs on computed tomography (CT) imaging. Steroid therapy was administered, as interstitial pneumonia was suggested; however, there was no improvement. A transbronchial lung biopsy (TBLB) revealed the possibility of distant lung metastases. Abdominal CT revealed pancreatic cystic lesions; the patient was, therefore, referred to our department for further evaluation. Endoscopic ultrasound revealed large multi-cystic lesion with mural nodule and wall thickness. A subsequent pancreatic juice cytology under endoscopic retrograde cholangiopancreatography revealed adenocarcinoma. As this was consistent with the pathological findings shown on TBLB, IPMC metastasis to the lung was diagnosed. In this case, it was considered that pulmonary lepidic metastasis from IPMC by CT imaging and pathological findings. Although the cases of pulmonary lepidic metastasis from gastrointestinal cancer are rare, we should consider these pathological conditions when pneumonia-like infiltration observed on imaging studies does not respond to treatment.