2020–2021 BCSC Basic and Clinical Science Course™
8 External Disease and Cornea
Chapter 9: Infectious Diseases of the External Eye: Basic Concepts and Viral Infections
DNA Viruses: Poxviruses
The Poxviridae are a large family of enveloped, double-stranded DNA viruses, with a distinctive brick or ovoid shape and a complex capsid structure. The best-known poxviruses are molluscum contagiosum, vaccinia, and smallpox (variola) virus.
Molluscum contagiosum virus is spread by direct contact with infected individuals. Infection produces 1 or more umbilicated nodules on the skin and eyelid margin and, less commonly, on the conjunctiva. Eyelid nodules release viral particles into the tear film.
A molluscum nodule is smooth, with an umbilicated central core. It is smaller and associated with less inflammation than a keratoacanthoma. Punctate epithelial erosions and, in rare cases, a corneal pannus may occur. Any chronic follicular conjunctivitis should instigate a careful search for eyelid margin molluscum lesions (Fig 9-21).
Figure 9-21 Multiple molluscum contagiosum nodules, associated with a follicular conjunctivitis in an immunocompetent child.
(Reprinted with permission from Tu EY. Conjunctivitis. In: Schlossberg D, ed. Clinical Infectious Disease. 3rd ed. New York: Cambridge University Press; 2008.)
LABORATORY EVALUATION AND MANAGEMENT
The molluscum contagiosum virus cannot be cultured using standard techniques. Histologic examination of an expressed or excised nodule shows eosinophilic, intracytoplasmic inclusions (Henderson-Patterson bodies) within epidermal cells. The diagnosis is based on detection of the characteristic eyelid lesions in the presence of a follicular conjunctivitis. Extensive facial and eyelid molluscum lesions may occur in association with AIDS (Fig 9-22). Spontaneous resolution occurs but can take months to years. Treatment options include complete excision, cryotherapy, or incision of the central portion of the lesion.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.