Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Thursday, August 24, 2006

What is Molluscum Contagiosum?

Molluscum Contagiosum
Definition: a viral infection, poxvirus, that produces one or multiple eyelid nodules
Incidence/Prevalence: comprises about 0.3% of eyelid biopsies at UCLA.
Etiology: The virus belongs to the poxvirus group and is somewhat rectangular or brick-shaped and measures 300 nm by 240 nm.
Clinical Findings: Patients present with a variable number of waxy, dome-shaped papules that have umbilicated centers and measure 1-4 mm in diameter. The fully developed lesions may have cheesy or curd-like material which can be expressed from the center. The lesions are frequently located near the lid margin and conjunctiva and may be associated with a follicular conjunctivitis. The lesions may spontaneously involute and in this phase may be accompanied by inflammation, pain and tenderness.
Histopathology: At low magnification the "domed papule" is divided into pear shaped nodules of proliferating epidermis which on the surface appear as volcanic micro craters (arrow 2) separated by the epidermal lips of the crater (arrow 1). The characteristic and key feature is the presence of molluscum bodies also known as Henderson-Patterson bodies in the depths of the "volcanos". These bodies appear about 1-2 layers above the basal cell layer (arrow 5) of the epidermis as pink to red inclusions (arrow 3) and progress to become large bright red inclusions in the upper layers of the epidermis. Finally, they may exceed the size of the original cell (arrows 3 in high mag images). The inclusions displace the nucleus and leave only a thin crescent of basophilic material. In the granular layer the inclusions at first are surrounded by blue granules (arrow 4) and eventually may even appear slightly basophilic in the upper layers. The stratum corneum or cornified layer is often disintegrated as the inclusions enlarge (arrow 2). At the peak the molluscum bodies may reach a diameter of 35 microns. Ultrastructure shows each inclusion is composed of brick shaped viruses with dumbbell shaped nucleoids surrounded by the amorphous layer of capsids.
Treatment: With a nodular shape and umbilicated center, a single Molluscum lesion may mimic and frequently can be misdiagnosed clinically as a basal cell carcinoma. Single lesions are frequently removed. Spontaneous involution also occurs.

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