Pulmonary adenocarcinoma with osseous metaplasia: a rare occurrence possibly associated with early stage?

Adenocarcinoma is the most common type of malignant pulmonary tumor, but osseous metaplasia of this tumor is extremely rare. To date, only 21 cases have been reported in the literature worldwide. Here, we report a case of primary pulmonary adenocarcinoma with benign osseous stromal metaplasia in a 60-year-old woman and discuss the pathogenesis of intratumoral ossification and review the relevant literature. We found that pulmonary adenocarcinoma with osseous metaplasia may be more likely to occur in early tumor stages.