[A Case of Breast Cancer That Developed Pulmonary Tumor Thrombotic Microangiopathy during Adjuvant Chemotherapy].

A 68-year-old woman underwent neoadjuvant chemotherapy for left breast cancer(triple negative type), cT2N3cM0, cStage ⅢC, and Bt+Ax(Ⅲ). The pathological diagnosis was ypT1aN2aM0, ypStage ⅢA, ER-, PgR-, HER2 score 1+, Ki- 67 25%. Adjuvant radiotherapy(50 Gy/25 Fr)was then administered, followed by capecitabine as adjuvant chemotherapy. Dyspnea occurred during administration of capecitabine, and computed tomography(CT)and blood test results suggested drug-induced interstitial pneumonia and disseminated intravascular coagulation(DIC). The patient was admitted, and steroid pulse therapy, anticoagulant therapy, and antibiotics were administered; however, the treatment was ineffective, and she died 3 days after admission. An autopsy provided a final diagnosis of pulmonary tumor thrombotic microangiopathy(PTTM). There is no established treatment for PTTM, and the prognosis is poor even with anticoagulant therapy and chemotherapy. The definitive diagnosis of PTTM is based on pathological findings; however, during respiratory failure, invasive tests such as lung biopsy are not recommended. Therefore, if a significantly worsening respiratory disorder develops, as in this case, chemotherapy should be considered for suspected PTTM.