Pulmonary tumour thrombotic microangiopathy or chronic thromboembolic pulmonary hypertension?—diagnosed by pulmonary wedge aspiration cytology using a Swan–Ganz catheter: a case report

Pulmonary tumour thrombotic microangiopathy (PTTM) is a malignancy-associated disease that causes fatal pulmonary hypertension (PH). Due to its rapidly progressive clinical course, antemortem diagnosis is often difficult. Pulmonary tumour thrombotic microangiopathy shares several clinical and imaging characteristics with chronic thromboembolic pulmonary hypertension (CTEPH), making differentiation between these two diseases challenging.

A 64-year-old woman with pancreatic cancer treated with chemotherapy presented with shortness of breath and cough over the past 5 months and was admitted due to a 2-week history of worsening dyspnoea and peripheral oedema. Transthoracic echocardiography found dilated right ventricle, interventricular septal flattening, and severe tricuspid regurgitation. Although contrast-enhanced computed tomography showed no evidence of pulmonary thromboembolism, pulmonary perfusion scintigraphy demonstrated multiple wedge-shaped defects in the peripheral regions of both lungs. Right heart catheterization confirmed pre-capillary PH, and pulmonary angiography revealed vascular narrowing of the peripheral pulmonary arteries. Based on the radiological findings and the relatively slow clinical course, CTEPH was initially suspected. However, pulmonary wedge aspiration cytology—performed by aspirating a blood sample via a Swan–Ganz catheter from the wedged position during right heart catheterization—revealed tumour cells, confirming the diagnosis of PTTM rather than CTEPH. Because of the poor prognosis, the patient received palliative care and died 2 months later.

Pulmonary tumour thrombotic microangiopathy is a rare but fatal cause of PH and is rarely diagnosed antemortem. Pulmonary wedge aspiration cytology is a minimally invasive and valuable tool that helps differentiate PTTM from CTEPH and plays a crucial role in guiding both diagnosis and management.