A 46-year-old woman was admitted to our hospital because of bloody and chest pain. Chest X-ray and CT scan revealed a 17-mm nodule in the left upper lobe, consolidations in both lower lobes, and mediastinal and hilar lymphadenopathy. CT-guided lung biopsy from the right lower lobe revealed tumor cell embolism, intimal fibrocellular proliferation of small arteries, fibrin thrombi and recanalization. Embolic tumor cells were adenocarcinoma and immunohistologial staining for TTF-1 was positive. The patient was diagnosed as having pulmonary tumor thrombotic microangiopathy (PTTM) associated with clinical stage IV primary lung adenocarcinoma. Although chemotherapy with carboplatin and paclitaxel resulted in improvement of pulmonary consolidations, multiple bone metastatic lesions appeared. The patient was subsequently treated with docetaxel, and gemcitabine thereafter. This was the first reported case of PTTM associated with lung cancer and diagnosed antemortem by CT-guided biopsy. This suggests that CT-guided lung biopsy may be useful for diagnosis of PTTM, and enable establishment of appropriate cancer chemotherapy.