Italian Journal of Anatomy and Embryology - contenuto non piu disponibile

The term vulnerable plaque is used to identify thrombosis-prone plaques and plaques with a high probability of undergoing rapid progression1, thus becoming responsible of acute coronary syndrome or stroke. The role of microcalcifications about 10 μm in diameter in atherosclerotic plaque vulnerability is still debated2-4. From a morphological point of view, microcalcifications are not so easy to detect just by observing paraffin-embedded histopathological sections (3-5 μm thick). Diffuse calcification can be observed using Von Kossa staining5 but such small calcifications cannot be accurately measured. A good characterization of microcalcifications may be achieved observing at light microscopy semithin sections obtained from epoxy resin-embedded tissue samples thinner than 1 μm. Therefore, on the basis of the method reported by D’Amico6 we have developed a simple, rapid and trichromic method, which considers the use of methylene blueazur B, basic fuchsine and alizarin red. Our aim was to analyze microcalcifications on semithin sections from epoxy resin embedded samples of carotid endarterectomies. Comparisons were performed between the present method and methylene blue-azur B (with or without basic fuchsine) followed or not by Von Kossa staining. Our method is simple and fast (ca. 2 min), gives a sharp general contrast for all structures, and allows to easy identify collagen and elastin. In addition, gray-green colour associated to intracellular lipid droplets evidences foam cells, which are particularly abundant in endarterectomies samples. Mast cells and their metachromatic granules are also well recognized. Calcifications over 0,5 μm are clearly recognizable. Microcalcifications are clearly distinguished from the extracellular matrix in spite of their reduced dimensions. Methylene blue-azur B-basic fuchsinealizarin red method is easy to use, reproducible, and is particularly suitable for the identification of microcalcifications in the morphological analysis of atherosclerotic plaques.