neovascularization does not typically occur, which helps differentiate CIN lesions from limbal stem cell failure.
Figure 8-3 Corneal intraepithelial neoplasia. (Courtesy of James Chodosh, MD.)
MANAGEMENT See the section Management of Atypical Epithelial Tumors.
Malignant Epithelial Lesions
Squamous cell carcinoma
Squamous cell carcinoma, a plaquelike, gelatinous, or papilliform growth, occurs in limbal and bulbar conjunctiva in the interpalpebral fissure zone of older individuals.
PATHOGENESIS Ultraviolet radiation is an important influence on the development of squamous cell carcinoma, but viral and genetic factors probably also play a role. Squamous cell carcinoma is more common and more aggressive in patients with compromised immunity and in those with xeroderma pigmentosum.
CLINICAL FINDINGS A broad base is usually present along the limbus. The lesion tends to grow outward with sharp borders and may appear leukoplakic (Fig 8-4). Although histologic invasion beneath the epithelial basement membrane is present, growth usually remains superficial, infrequently penetrating the sclera or Bowman layer. Pigmentation can occur in dark-skinned patients. Engorged conjunctival vessels suggest malignancy. Note that CIN and invasive squamous cell carcinoma may have similar
clinical appearances (compare Figures 8-2C and 8-4).
Figure 8-4 Limbal squamous cell carcinoma.
MANAGEMENT See the section Management of Atypical Epithelial Tumors.
Management of Atypical Epithelial Tumors
The general approach to management of CIN and squamous cell carcinoma of the conjunctiva and cornea is detailed earlier in the chapter (see the subsections Surgical Treatment and Topical Chemotherapy). These tumors have a high recurrence rate, which varies from 33% to 50%, in eyes with negative surgical margins and those with positive surgical margins, respectively. Rose bengal or lissamine green staining may be useful to help delineate tumor margins and may increase the likelihood of complete excision. Chemotherapy using topical interferon-α2b, MMC, or 5-FU treats the entire ocular surface and is a useful adjunct in the management of squamous tumors. Figure 8-5 summarizes the various treatment options for CIN and invasive squamous cell carcinoma.
Figure 8-5 Treatment options for conjunctival intraepithelial neoplasia and invasive squamous cell carcinoma. 5-FU = 5-
fluorouracil; IFN-α2b= interferon-α2b; MMC = mitomycin C. (Reproduced from Koreishi AF, Karp CL. Ocular surface neoplasia. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2007, module 1.)
If neglected, squamous cell carcinoma can eventually invade the interior of the eye, where the tumor can exhibit vigorous growth. Invasion of the iris or trabecular meshwork provides the tumor with access to the systemic circulation and may be the route by which metastases occur. Orbital invasion may require orbital exenteration. Radiation therapy may be indicated as adjunctive therapy in select cases.
Other Malignant Epithelial Lesions
Mucoepidermoid carcinoma
Mucoepidermoid carcinoma—a very rare carcinoma of the limbal conjunctiva, fornix, or caruncle— clinically resembles an aggressive variant of squamous cell carcinoma. In addition to neoplastic