A MORPHOLOGIC STUDY OF THE VASCULATURE OF MALIGNANT GLIOMAS USING THICK CELLOIDIN SECTIONS AND ALKALINE PHOSPHATASE STAIN

Abstract

The combination of 100 microm thick celloidin sections and alkaline phosphatase (AP) enzyme histochemistry of the vascular endothelium offers a greatly enhanced, 3D morphologic perspective and reveals intricate details of the vasculature of brain. A study of tumor specimens obtained at craniotomy from 6 patients with glioblastomas, 1 with anaplastic oligodendroglioma and 1 with juvenile pilocytic astrocytoma was undertaken using this technique. Five of the 6 glioblastomas, the anaplastic oligodendroglioma and the low-grade astrocytoma specimen showed uniform staining of afferent tumor blood vessels. In the glioblastomas, newly formed vessels formed dense, festooned networks at the advancing edges of the tumor. Feeding arteries entered the tumor at the junction between the edge of the tumor and adjacent brain or meninges and proceeded to form striking, coiled vessels and smaller branches. The density of both small arteries and veins was greatly increased within the tumor although there was much variability. Disordered arborization, arteriole to venous and arteriole to arteriole shunts were observed, leading to a situation where arteries connected directly to veins. In necrotic areas, there were often no AP-stained vessels. In many places, arterioles and capillaries were lacking. Numerous AP-negative veins of various sizes drained the tumors. Glomeruloid proliferations were presumptively identified as focal stain smudges or clusters of capillaries arising from nearby vascular channels. Increased alkaline phosphatase staining and/or focal new vessels were seen outside necrotic areas. The pilocytic astrocytoma and the oligodendroglioma showed less dense vascularity and no formation of the focal festoons of vessels shown by the glioblastomas. This technique may be useful for the study of tumor angiogenesis and to evaluate vascularity in experimental and human brain tumors after various therapies.