Vascular tree-in-bud sign in Pulmonary Tumour Thrombotic Microangiopathy (PTTM): CT findings for a difficult radiological early antemortem diagnosis

.Pulmonary tumour thrombotic microangiopathy (PTTM) is a rare clinic-pathological disease entity in which the tumour cells embolize into the pulmonary vasculature inducing thrombotic microangiopathy. Although it has been observed in 0.9%-3.3% of autopsy case studies with extra-thoracic malignancies, rarely is it diagnosed antemortem. PTTM should be suspected in the appropriate clinical setting and confirmed by lung biopsy, that demonstrates pulmonary tumour emboli within pulmonary vasculature surrounded by fibrin deposition and fibrocellular intimal proliferation