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- When Bronchovascular Bundle Thickening Signals More: CT–Histopathology Correlation in Canine Pulmonary Carcinoma
When Bronchovascular Bundle Thickening Signals More: CT–Histopathology Correlation in Canine Pulmonary Carcinoma
Vet Radiol Ultrasound. 2026
Obi Veterinary Education
February 17, 2026
Robert Wise, Maria Mulvihill, Jennifer Reetz, Bianca Pfisterer, Wilfried Mai
Background
Pulmonary metastases in dogs are typically characterized by nodular soft tissue opacities on thoracic imaging. However, atypical presentations such as bronchovascular bundle thickening (BVBT) have been sporadically described. In human medicine, similar CT findings are often associated with lymphangitic carcinomatosis, though multiple metastatic pathways—including hematogenous and aerogenous routes—are recognized. The purpose of this study was to correlate CT-detected BVBT in dogs with histopathologic findings to better characterize the underlying metastatic pathways and determine whether BVBT corresponds specifically to lymphangitic spread or reflects multiple mechanisms of pulmonary metastasis.
Methods
This retrospective, descriptive cross-sectional study reviewed CT studies performed between 2007 and 2024 at a single veterinary teaching hospital. Dogs were included if they had a pulmonary mass with associated BVBT on CT and corresponding histopathologic lung evaluation from surgical biopsy or necropsy that allowed direct imaging–pathology correlation. CT images were reviewed by radiology residents and board-certified radiologists, and histopathologic slides were reevaluated by a board-certified pathologist. Metastatic pathways were classified as hematogenous, lymphangitic, lymphovascular, or aerogenous based on the distribution of neoplastic cells.
Results
Out of over 1000 CT studies reviewed, 138 met initial imaging criteria, and three dogs ultimately fulfilled inclusion criteria with adequate histopathologic correlation. All dogs had a single primary pulmonary carcinoma (one adenocarcinoma and two unspecified carcinomas). BVBT was ipsilateral and multilobar in two dogs and unilobar in one dog. Histopathology revealed lymphovascular invasion in two cases and lymphangitic invasion in one case. All three cases demonstrated aerogenous metastasis, with neoplastic cells identified within bronchioles, alveoli, and/or alveolar septa. BVBT corresponded histologically to peribronchial/peribronchiolar interstitial expansion with neoplastic infiltration of lymphatic vessels, blood vessels, or both, often accompanied by desmoplasia.
Limitations
The primary limitations were the retrospective design and small sample size. Although numerous CT studies demonstrated BVBT, only three cases had histopathologic samples that directly corresponded to regions of imaging abnormalities, limiting generalizability. The single-institution setting further restricts broader application of findings.
Conclusions
Bronchovascular bundle thickening on CT in dogs can be associated with metastatic carcinoma and corresponds histologically to peribronchial/peribronchiolar lymphatic, vascular, and aerogenous neoplastic infiltration. BVBT does not appear specific to a single metastatic pathway. The findings suggest that the term “lymphangitic carcinomatosis,” commonly used in human medicine, may not fully encompass the spectrum of metastatic mechanisms responsible for this imaging pattern in dogs. Further studies with larger cohorts and detailed histopathologic correlation are warranted to clarify CT characteristics of distinct metastatic pathways in veterinary patients.
Transverse (A) and dorsal plane reformatted (C) CT images and corresponding histopathologic images at 20× magnification (B and D) of Case 2. (A) Bronchovascular bundle thickening (center of the black square) in the right caudal lung lobe adjacent to a primary pulmonary adenocarcinoma (+). Ground glass opacity, in addition to BVBT, along the ventral periphery of the mass, is present (black open brackets). (B) Histological sample taken from the area in the black square in (A), including the mass (+) and adjacent bronchovascular bundle thickening, demonstrating a bronchus (*) surrounded by collagen and islands of neoplastic cells (long black arrows). (C) Multilobar ipsilateral bronchovascular bundle thickening is present in the right caudal and right cranial lung lobes, adjacent to and extending distant to the mass (dashed arrows). Bronchovascular bundles are normal in the left lung. (D) Histological sample taken from the area in the black open bracket in (A) demonstrating primarily vascular metastases (long black arrows) and septal thickening (short black arrows). CT images: window width 1500, window level −700.
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