The histogenesis of molluscum contagiosum.

In the group of viral induced epidermal hyperplasias, the inverted, follicular, and lobulated pattern of a lesion of molluscum contagiosum is distinctive. The proposed epithelial progenitors have included epidermis, sebaceous glands, and hair follicles. A study of 77 cases of molluscum contagiosum implicates folliclular neogenesis as a primary histogenetic determinant. Areas of hair bulb differentiation are common at the periphery of a lesion of molluscum contagiosum and occasionally are associated with areas of sebaceous gland differentiation. In areas of active viral replication, the neogenetic follicular epithelium expands to form rounded lobules which extrude viral particles and keratinized debris into dilated ostia. In inflamed molluscum contagiosum, the inflammatory response is reminiscent of the invasive--destrictive pattern of cell-mediated immunity.