Pulmonary tumour thrombotic microangiopathy in a patient with metastatic colorectal adenocarcinoma – a case report.

Abstract

Pulmonary tumour thrombotic microangiopathy (PTTM) is a rare end stage complication of malignancy with patients presenting with progressive and worsening dyspnoea secondary to increased pulmonary vascular resistance and subsequent right heart failure. First described by Herbay PTTM is a clinicopathological diagnosis usually made post mortem, with the presence of tumour microemboli associated with fibrous intimal hyperplasia of the pulmonary vasculature. A high degree of clinical suspicion is required as the prognosis without treatment is grim, typically days to weeks. We report a 36-year-old male who presented with four days of dyspnoea on a background of recently diagnosed metastatic carcinoma of unknown primary. He was initially investigated for pulmonary embolus, however subsequent computed tomography pulmonary angiography (CTPA) showed no abnormality. Echocardiography revealed signs of acute right heart failure secondary to elevated pulmonary vascular resistance (PASP 82 mmHg, N 18–25). Despite anticoagulation, antibiotics and ICU support, the patient passed away within 24 hours of his admission. Autopsy revealed a sigmoid tumour, widespread lymphadenopathy and peritoneal deposits, with microscopy and immunohistochemistry confirming poorly differentiated colorectal adenocarcinoma within the sigmoid tumour and metastatic deposits. Atypical cells associated with thrombus and fibrous intimal hyperplasia in pulmonary vasculature confirmed PTTM as the cause of death.