fig 7.

Histologic findings.

A, Gross view of one brain specimen after formalin fixation and coronal section. The lesion was dissected in the center. The frontal section on the left shows sharply delineated necrosis (large arrowhead) in the right hemisphere and a small rim of extravasated blood (arrow). The directly following parietal specimen on the right was turned over, so the same lesion is now seen on the left. Necrosis (large arrowhead) and rim of extravasated blood (arrow) are identical. Iatrogenic lesion of the dura mater (small arrowhead) is inconspicuous. Note the absence of general brain edema and severe hemorrhage.

B, Histologic detail of cryolesion and neighboring cortex. Meninges (small asterisk), cerebral cortex with neuronal layer (small arrowhead), and following subcortical white matter are seen above and are unaffected. Transition zone (bar) next to the lesion consisting of vital, edematously, and spongiously altered tissue. Neurons are damaged selectively, when they are involved. Many capillaries (large arrowheads) were observed sprouting from this area and leading into the outer zone of necrosis. In this outer zone (medium asterisk), numerous leukocytes and macrophages were seen. Neutrophils and lymphocytes were also present, in variable composition. In the center of the necrosis (large asterisk), amorphous necrotic tissue with corresponding paleness of nuclei, cell bodies, and fibers was observed (hematoxylin and eosin; original magnification, ×60).