Histopathologic Findings in Three Dogs With Metastatic Carcinoma Presenting With Bronchovascular Bundle Thickening on Computed Tomography.

Carcinoma metastasis to the lungs can occur via multiple pathways, most notably via hematogenous, lymphangitic, or aerogenous routes. Computed tomographic (CT) characteristics of these metastatic pathways can vary, with only sparse reports of bronchovascular bundle thickening (BVBT) associated with metastatic carcinoma. In this retrospective cross-sectional study, three dogs with metastatic carcinoma and BVBT on CT that had corresponding histopathological sections at the site of BVBT were reviewed. These cases showed expansion of the peribronchial/peribronchiolar interstitium with islands of neoplastic cells within the stroma and either lymphatic infiltration alone or hematogenous and lymphatic infiltration combined (lymphovascular), along with neoplastic cells in the airways and/or septal lining of the alveoli. On the basis of this study, BVBT on CT in dogs can be seen with metastatic carcinoma, associated with peribronchial/peribronchiolar lymphovascular and aerogenous metastases. Additional studies are needed to characterize each metastatic pathway and further correlate histopathological findings with CT appearance.