Infectious Inflammatory Disorders
Depending on the causative agent, infectious organisms can cause disease that is localized (eg, hordeolum), multicentric (eg, papillomas), or diffuse (eg, cellulitis). Common routes of infection include primary inoculation through a bite or wound and direct spread from a contiguous site, such as an infected paranasal sinus. Infectious agents may be
bacterial, such as Staphylococcus aureus in hordeolum and infectious blepharitis
viral, such as poxvirus in molluscum contagiosum
parasitic, such as Demodex folliculorum
Hordeolum A hordeolum (also called a stye) is an acute, generally self-limited primary inflammatory process typically involving the glands of Zeis and, less often, the meibomian glands. A small abscess, or focal collection of neutrophils and necrotic debris (ie, pus), forms at the site of infection, which is usually caused by S aureus. Lesions may drain spontaneously or require surgical management.
Cellulitis The diffuse spread of acute inflammatory cells through tissue planes is known as cellulitis. Preseptal cellulitis involves the tissues of the eyelid anterior to the orbital septum, which is the collagenous membrane connecting the nonmarginal borders of the tarsal plates to the bony orbital rim. Cellulitis is most often secondary to bacterial infection of the paranasal sinuses. Histologic examination reveals neutrophilic infiltration of the soft tissues, accompanied by interstitial edema and, occasionally, necrosis (Fig 13-3). See BCSC Section 7, Oculofacial Plastic and Orbital Surgery, for additional discussion.
Human papillomavirus may infect the skin of the eyelids, typically manifesting as verruca vulgaris, or wart. Clinically, verruca vulgaris is usually an elevated lesion with fine papillary projections. Histologically, the lesions exhibit a papillary growth pattern and demonstrate parakeratosis, hyperkeratosis, and acanthosis (Fig 13-4A). Infected epidermal cells may show cytoplasmic clearing (koilocytosis) (Fig 13-4B). A mixed inflammatory cell infiltrate is typically present in the superficial dermis.
In molluscum contagiosum, which is caused by a member of the poxvirus family, small waxy, dome-shaped epidermal nodules with central umbilication form. When the nodules are present on the eyelid margin, an associated follicular conjunctivitis may develop because of shedding of virus onto the conjunctival surface (Fig 13-5). Histologically, the lesions are distinctive in appearance (Fig 13-6).
Figure 13-3 Biopsy from a case of preseptal cellulitis of the eyelid. Neutrophils (arrows) infiltrate between the skeletal muscle fibers (asterisks) of the orbicularis oculi muscle.
Figure 13-4 Verruca vulgaris. A, Verruca vulgaris is a form of human papillomavirus (HPV) infection of the eyelid epidermis. The resulting “wart” has a papillary growth pattern with fingerlike projections. B, Occasional koilocytes with nuclear contraction and cytoplasmic clearing are present (arrow).
(Courtesy of Nasreen A. Syed, MD.)
Infection of the eyelid with the mite Demodex folliculorum is increasingly recognized as a cause of chronic eyelid and conjunctival inflammation. The conditions caused by this parasite are discussed in more detail in BCSC Section 8, External Disease and Cornea.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.