Pulmonary metastatic microangiopathy of colon cancer presenting as a "tree in bud" pattern.

The authors report an unusual case of a "tree in bud" pattern of vascular origin caused by colon cancer metastases. A 60-year-old man presented for routine follow-up of a colon tumour resected surgically 15 years previously. Clinical examination, laboratory tests, including carcino-embryonic antigen and inflammatory parameters, and chest radiograph were normal. Multislice CT of the lungs revealed the presence of several "tree in bud" opacities. The connection to the pulmonary arteries was well depicted by reformatted maximal intensity projection images. Biopsy of some of the nodules was characterized by mucinous material and neoplastic cells within the small vessels, consistent with metastases from the known colon adenocarcinoma.