Histology of a variola maculopapular lesion (500x magnification)

The predominate layer in this particular image is the stratum spinosum and cells demonstrating "ballooning degeneration", which is the intracellular swelling that eventually will lead to cellular lysis. The coalescence of these ruptured cells leads to the formation of microvesicles. The outward growth of the maculopapular lesion is due to the formation of these microvesicles, which are filled with an infiltration of proteinaceous material, inflammatory cells, and cellular debris. Arrow points to a Guarnieri body.