Diffuse pulmonary ossification most commonly occurs in men in their fifth and sixth decades of life and is usually associated with diffuse and chronic lung disease, cardiac disease, or other systemic disorders. In this report, we describe a case of dendriform pulmonary ossification with a past history of giant cell tumor in the femur that occurred 8 years before. The nodules mimicked calcified pulmonary metastases. The patient was young (30 y old) and had no chronic lung or cardiac diseases. We speculate that the pulmonary ossification might have been due to dissemination of bone cells into the pulmonary circulation during bone curettage.