A 78 year-old male complained of mild pain at a gingival mass on his anterior mandible, injured and ulcerated by autobicycle accident six months ago. He had suffered from uncontrolled diabetes. The tumor specimens from his chin and gingiva were examined by immunohistochemical method, and their microsections showed poorly differentiated polygonal tumor cells, occasionally formed ductal structures. The tumor cells grew infiltratively into adjacent fibromuscular tissue with frequent atypical mitosis, exhibiting the features of poorly differentiated adenocarcinoma. However, in the computed tomography(CT) view a tumor mass was also found in his lung, and diagnosed lung cancer. In the immunohistochemical observation the tumor cells were strongly positive for thyroid transcription factor 1(TTF-1), cytokeratin 7, PCNA, p53, and PIM-1, occasionally positive for p63, but sparsely positive for survivin. The tumor cells were almost negative for S-100, cytokeratin 14, and α-SMA, while the vascular structures in the tumor tissue were conspicuously demarcated by the stains of α-SMA. Taken together, the present case was finally diagnosed poorly differentiated adenocarcinoma, metastasized from lung adenocarcinoma. And it was presumed that the metastatic tumor cells tended to be anchored in the traumatized area of anterior mandible, where the wound healing was undergoing with de novo angiogenesis and the activation of different cytokines and growth factors