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Figure 1. 60-year-old woman with a metastatic pulmonary microangiopathy of a colon cancer. (a) Thin-slab maximal intensity projection (MIP) frontal reformatted CT images (at lung window settings) show multiple linear branching opacities connected to the peripheral pulmonary arteries in both the right-lower lobe and left-upper lobe (straight arrows). This represents the "tree in bud" sign, in relation to the multiple endovascular tumour emboli. Note a right liver lobe resection related to previous surgery for a liver metastasis. (b) Thin-slab MIP axial reformatted CT focused on the right lung illustrates, at lung window settings, the arborescent aspect of the vascular abnormalities (straight arrows). (c) Photomicrograph of the open lung biopsy, which shows a vessel lumen occluded by mucus (left-hand side; arrowhead) and another vessel containing neoplastic cells together with mucus and an organizing thrombus (right-hand side; arrows) (left-hand image: x2.5, right-hand image: x20).
