A Case of Pulmonary Enteric Adenocarcinoma with Calcification

Abstract

Background. Pulmonary enteric adenocarcinoma is a rare type of non-small-cell lung cancer showing a histological pattern mimicking metastatic colorectal cancer. Case. A man in his 60s was referred to our hospital because of an abnormal shadow on a chest radiograph during follow-up for prostate cancer. Chest computed tomography (CT) showed a 50-mm mass with multiple small calcifications in the left upper lobe. The peripheral area of the left upper lobe showed obstructive atelectasis. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) showed an increased FDG uptake in the mass of the left upper lobe (maximum standardized uptake value [SUVmax] 12.7), mediastinal lymphadenopathy, and left supraclavicular lymphadenopathy. A bronchoscopy specimen showed tumors that formed ducts composed of tall columnar cells. Immunohistochemical staining demonstrated CK7 (−), CK20 (focally＋), TTF-1 (−), CDX2 (＋), and Napsin A (−) expression. The findings indicated pulmonary enteric adenocarcinoma or metastatic colorectal carcinoma. The patient was clinically diagnosed with pulmonary enteric adenocarcinoma (cT2bN3M0, cStage IIIB), as no evidence of a tumor was found elsewhere by colonoscopy. He underwent chemoradiotherapy. Subsequent CT revealed shrinkage of the tumor. Conclusion. We encountered a patient with pulmonary enteric adenocarcinoma with calcifications. The CT findings of pulmonary enteric adenocarcinoma are similar to the imaging findings for invasive pulmonary adenocarcinoma and metastatic colorectal cancer. Distinguishing between these two entities by imaging alone is difficult.