The Potential Role of Inflammation Associated with Interaction between Osteopontin and CD44 in a Case of Pulmonary Tumor Thrombotic Microangiopathy Caused by Breast Cancer

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare and fatal cancer-related complication. We herein present a case of PTTM that diagnosed antemortem by lung scintigraphy and pulmonary microvascular cytology. The patient was treated with steroid pulse therapy. Although her symptoms temporarily improved, she died of respiratory failure. An autopsy showed PTTM, and an immunohistochemical analysis revealed the expression of osteopontin and CD44 in macrophages that had migrated into the PTTM lesions. These findings suggest that inflammation associated with the interaction between osteopontin and CD44 may play an important role in PTTM.