A Rare Case of Metastatic Brain Tumor From Classic Biphasic Pulmonary Blastoma Presented as Intracerebral Hemorrhage

Pulmonary blastoma is a rare type of primary lung cancer that accounts for only 0.25%–0.5% of all lung malignancies. Pulmonary blastoma consists of three subgroups: classic biphasic pulmonary blastoma (CBPB), pleuropulmonary blastoma, and well-differentiated fetal adenocarcinoma. Due to the rarity of the tumor, metastatic brain tumor from CBPB is extremely rare, and only 13 cases, including our case, have been reported. A 60-year-old woman who underwent left upper lobectomy of the lung because of pathologically diagnosed as CBPB 5 months ago, suddenly lost consciousness and presented with stupor mental status. The emergent CT scan showed a large, 51 mL, intracerebral hemorrhage on left parieto-occipital lobe with midline shifting. The patient underwent emergent craniotomy, and a hypervascular tumor was identified during the operation. Histopathologic examination reported metastatic pulmonary blastoma, CBPB. The patient has been in a vegetative state, but there has been no evidence of recurrence over a 6-month follow-up period. We report a rare case of brain metastasis from CBPB presenting with altered mentality due to massive tumor bleeding. This is the only reported case of brain metastasis from CBPB presenting with acute intracerebral hemorrhage.