Well-differentiated fetal adenocarcinoma (WDFA) of the lung is a rare, primary, low-grade, bronchopulmonary neoplasm characterized by a well-circumscribed, usually large, pulmonary mass that is histologically composed of glycogen-rich neoplastic glands and tubules that resemble fetal lungs at 10 to 16 weeks of gestation and benign adjacent stroma. It typically presents with chest pain, cough, dyspnea, hemoptysis and/or generalized, non-specific symptoms, such as night sweats, lethargy, poor appetite and weight loss. The disease is MONDO_0017292 (well-differentiated fetal adenocarcinoma of the lung). Also known as: WDFA, fetal adenocarcinoma, fetal lung adenocarcinoma, foetal adenocarcinoma, foetal lung adenocarcinoma, pulmonary adenocarcinoma of fetal type, pulmonary adenocarcinoma of foetal type, pulmonary endodermal tumor resembling fetal lung.