Primary pulmonary cancer colliding with metastatic choriocarcinoma

Collision tumors are rare in nature. Although lung is one of the main organs where metastatic tumors may occur, collision neoplasms consisting of a primary lung cancer and metastatic choriocarcinoma have never been reported so far. Here we describe a case of primary squamous-cell lung carcinoma (SCC) colliding with metastatic choriocarcinoma in a 55-year-old woman.