Basement-membrane-related peri-vascular matrices not organised as a basal lamina: distribution in malignant tumours and benign lesions.

Abstract

Peri-vascular matrices having a finely textured granular substructure have been identified in 27 human lesions: these were mostly malignancies but included benign tumours and reactive processes. The matrices were defined as stromal components surrounding endothelium and pericytes, and lying between vessels and adjacent lesional cells. They were identified as having a finely textured, uniform and moderately dense substructure, and differed from a conventional basal lamina expected at these sites by the absence of the typical lamina densa/lamina lucida configuration. By light microscope immunohistochemistry, vessels stained positively for laminin and collagen IV, two of the main proteins characterising a conventional basal lamina. The present observations emphasise the following. 1) The proteins laminin and collagen IV can be found in peri-vascular locations which have a finely textured granular substructure, and which have clearly defined ultrastructural differences from a conventional basal lamina. 2) While conventional light microscope immunohistochemistry demonstrates the presence and cellular location of proteins, electron microscopy is helpful for giving information on their physical organisation. 3) Peri-vascular granular matrices have a widespread distribution in malignant tumours but also exist in benign tumours and reactive lesions. This paper briefly discusses the possible functions of these matrices as modulators of cell biological processes.