What histopathological changes can be seen post-VTP treatment?

The post-VTP treatment typically results in tissue necrosis, inflammation, and vascular occlusion due to the mechanism of action inherent in photodynamic therapy. Vascular Targeted Photodynamic therapy utilizes a photosensitizing agent that is preferentially absorbed by the abnormal tissue, particularly tumor cells. Upon activation by light, the photosensitizer generates reactive oxygen species, which leads to damage of the vascular endothelium and subsequent occlusion of blood vessels within the targeted area.

This vascular damage causes localized ischemia, resulting in necrosis of the treated tissue. Additionally, the inflammatory reaction is a response to that tissue damage, helping to recruit immune cells to the site to clear away necrotic debris. In essence, the changes observed—such as necrosis, inflammation, and vascular occlusion—are direct outcomes of the therapeutic effects intended to destroy malignant tissues while sparing surrounding healthy cells to the greatest extent possible. These outcomes are critical for assessing the efficacy of VTP in clinical settings and understanding its histopathological impact on tissues.