ULTRASTRUCTURAL CHANGES IN DERMAL AND EPIDERMAL CELLS OF SKIN INFECTED WITH MOLLUSCUM CONTAGIOSUM VIRUS

This study of molluscum-infected skin includes heretofore unreported ultrastructural details of dermis subjacent to the molluscum-infected epidermis. Nuclei of certain cells within the suprabasal or lowest layer of the stratum Malpighii contained multiple electron dense granules [similar to those in nuclei of cultured cells showing molluscum cytotoxic effect (4)]. The cytoplasm of cells in this layer appeared uninvolved. Infected cells in and above the upper Malpighian cell layer exhibited the following changes: electron opaque intra-nuclear granules; the cytoplasm was progressively replaced by non-membrane-bounded vacuoles containing large aggregates of mature virus particles; the septae of ground substance, separating these vacuoles, contained particles which could represent nascent or incomplete virus. Mature virus particles had dense biconcave nucleoids and less dense granular viroplasm the two being separated by an electron lucent area. Mature viral particles were not found in the dermis nor basal cell layer. Collections of hyperplastic fibroblasts, containing bizarre nuclei, were present in the dermis subjacent to the lesion. Inflammatory cells were conspicuously absent. No abnormality of nonmyelinated nerve fibers, endothelium of capillaries, arterioles and venules, or melanocytes was noted. The polarity of the lesion and the absence of mature virus particles below the Malpighian layer support the hypothesis that molluscum infections are transmitted by external contact. © 1969 Academic Press, Inc.