THE ULTRASTRUCTURE AND HISTOGENESIS OF MOLLUSCUM CONTAGIOSUM

Three-dimensional ultrastructural study of molluscum contagiosum in the skin using scanning-electron microscopy

The three-dimensional ultrastructure of molluscum contagiosum virus (MCV) in human skin was visualized using scanning-electron microscopy with the osmium-dimethyl sulphoxide-osmium method. There were spherical, ellipsoidal, brick-shaped, miniature and incomplete forms of MCV. In all the forms the surface had densely distributed small protrusions and all had the same ultrastructure. All the forms had one or two long cord-like substances that appeared to be linked together, but became short, vestigial or absent on the surface of the mature virus. The cord-like substances were connected to the core of the MCV. In the matrix between the viruses, the cord-like substances formed an intricate fine network.

Molluscum contagiosum associated with AIDS: a case report with ultrastructural study

The clinical features of perioral molluscum contagiosum in a patient with the acquired immunodeficiency syndrome are described. Light microscopy and thin section electron microscopy revealed epidermal cells in different stages of degeneration showing two types of cytoplasmic inclusions. The basement membrane exhibited discontinuities and multiple laminations which may be a response to viral-induced cytotoxic effects.

Fine structure of palpebral molluscum contagiosum and its secondary conjunctival lesions

One case of molluscum contagiosum of the lid, which has been followed by follicular conjunctivitis and superficial punctate keratitis, has enabled us to compare the ultrastructure of the skin tumor and of the conjunctival lesion. Electron microscopic observation is the only way for discovering the causal Poxvirus. Up to now isolation of the viral strain has not been possible. Examination of the skin tumor showed different maturation forms of the virus and associated cell alterations. In the conjunctiva there was an inflammatory reaction, with exocytosis and infiltration of the chorion by lymphocytes and plasma cells. Intracytoplasmic organelles were formed in the superficial epithelial cells. Their size and structure resembled that of the immature virions found in the epidermic cells. The comparison between skin and conjunctival lesions suggests the following sequence of events in the pathogenesis: the virus, leaving the lid tumor, probably penetrates the conjunctival cells and, without finding the conditions necessary for its full development, produces abnormal viral inclusions unable to become a mature virus. The excision of skin nodules thus cures the infection, since it prevents further reinfection by the skin virus. The morphological criteria on which this hypothesis is based must be confirmed by chemical and morphometrical studies.