S11C27P22Molluscum


S11C27P22-1: The characteristic papule of molluscum contagiosum is a multi-lobulated, epithelial hyperplasia in inverted patterns. The epithelial component has a follicular configuration. Cavitated columns of squamous cells have bulbous extremities; the cavitated columns might be compared to the infundibulum of a hair follicle. The bulbous extremities, in their configurations, might be compared with the sebaceous gland lobules of a follicle. The stroma is a watery, clear matrix. Occasionally, at the extremities of the columns, patterns of abortive hair matrix differentiation (buds of basal cells) will be represented.

S11C27P22-2: Bulbous expansions are closely spaced in this area. They are outlined by a thin sheath of fibrous tissue. Cytoplasmic inclusions first appear at a level of 4 or 5 cell layers above the basement membrane. They become more numerous and more mature at superficial levels; they eventually are discharged into a common lumen that usually communicates with the surface of the skin. Near the surface the affected epithelium shows hypergranulosis. In the keratin layer, the inclusions are condensed, but preserved, among the keratinized lamellae. Obviously, not all the keratinocytes of the affected area contain viral inclusions; those, which do not, differentiate into the flattened keratinized lamellae.

S11C27P22-3: Near the bottom of the field, keratinocytes show ballooning degeneration. They show pale, or vacuolated cytoplasm. They are enlarged and rounded in outline. In these cells, nuclei are centrally placed. At the next level towards the surface, cytoplasmic inclusions are prominent and are closely clustered. The nucleus of these cells have been displaced laterally; the nuclei are compressed by the inclusion. In the granular layer, the inclusions are prominent. Keratinocytes, which do not contain viral inclusions, are compressed among those that do.

S11C27P22-4: This is an example of inflamed, cystic molluscum contagiosum; it is not an epidermoid cyst that has been secondarily infected. In a lesion of this type, the infected epithelium loses its ostium at the surface. The lesion then evolves to produce a cyst whose contents include not only keratinized debris, but also the condensed inclusions of molluscum contagiosum.

S11C27P22-5: This lesion of molluscum contagiosum is heavily inflamed. Blue arrows identify a sequestered island of infected epithelium. It is isolated in inflamed granulation tissue. A cleft has formed at the interface between the epithelium and the granulation tissue; the infected epithelium is on its way to becoming a sequestrum. The ragged surface with scattered, irregular defects is partially necrotic. The defects are sites in which infected islands of epithelium have undergone lysis, or have been extruded along the surface. The infiltrate in the granulation tissue is rich in lymphocytes and histiocytes (inflamed molluscum contagiosum).

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