Well-differentiated fetal adenocarcinoma: rare tumor in the pediatric population.

Well-differentiated fetal adenocarcinoma (WDFA) is a rare tumor of the lung, which has gone by many names over the years. The lesion was first described by Kradin et al., in 1982, who called it "pulmonary blastoma with argyrophil cells and lacking sarcomatous features (pulmonary endodermal tumor resembling fetal lung)." Since then, there have been at least 65 cases reported in the literature. Although there has been no consensus in the literature as to the best pathological term for this entity, the most recent World Health Organization classification of lung and pleural tumors uses the term well-differentiated fetal adenocarcinoma. Characteristically, this lesion consists of an epithelium, which recapitulates fetal lung at 3-5 months of gestation and demonstrates neuroendocrine differentiation. Although the classic age range is 30-40 years, there have been seven reports of WDFA in the pediatric age. We report an additional pediatric case of this tumor and review the pediatric cases in the existing literature.