A 30-year-old female with no significant past medical history was referred to our facility with sudden onset of shortness of breath. She had a low clinical probability for pulmonary thromboembolism and a computed tomography angiogram showed enlarged pulmonary arteries but no in situ thrombi. She developed recurrent episodes of hypotension and hypoxia, and was transferred to the intensive care unit where she died despite active resuscitation. An autopsy revealed extensive lymphatic and pulmonary vascular tumour emboli as the immediate cause of death. Pulmonary tumour embolism is a very rare cause of death, but can occur in patients who have an occult neoplasm.