Unusual presentation of pulmonary tumor thrombotic microangiopathy with no detectable primary tumor

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare condition characterized by the presence of diffuse thrombotic microthrombi and fibrocellular intimal proliferation in the pulmonary vasculature. Its development is linked to the presence of pulmonary tumor microemboli (PTM) and should be suspected in patients with unexplained dyspnea, especially in the presence of adenocarcinoma. PTTM presents in a similar fashion to respiratory disease such as pulmonary embolism, pulmonary hypertension or pneumonia and is usually only diagnosed post-mortem. We report a case of PTTM identified ante-mortem by bronchial biopsy in an 82-year-old woman presenting with a clinical picture of atypical pneumonia. Autopsy confirmed PTTM, from an unknown primary neoplasm.