Pulmonary hypertension and cor pulmonale due to tumor emboli causing pulmonary tumor thrombotic microangiopathy (PTTM) is rare and extremely difficult diagnosis to make prior to death. Pulmonary hypertension due to metastatic tumor emboli should be included in the differential diagnosis of various causes of dyspnea in patients with a history of cancer or more common causes, including infection, thromboembolism, metastasis, adverse effects of drugs, and recurrent effusions. We describe a patient with gallbladder carcinoma who presented with progressive dyspnea and severe pulmonary hypertension. The etiology was tumor emboli and PTTM from gallbladder carcinoma, which remained elusive prior to her death despite appropriate clinical investigations and was established on autopsy. To the best of our knowledge, this is likely the second reported case of PTTM from metastatic gallbladder carcinoma.