EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78710
48 EW CORNEA May 2012 Cornea editor's corner of the world Treating ocular surface squamous neoplasia by Michelle Dalton EyeWorld Contributing Editor O cular surface squamous neoplasia (OSSN) is not a common condition but is one that all clinicians need to be able to recognize. An early diagnosis with a small lesion results in a very good prognosis. However, a delay in diagnosis can lead to a lesion that involves a large area of epithelium including a significant amount of the limbal stem cells and con- junctival. Treating these larger lesions is more difficult and has a higher recurrence rate. All clinicians should be aware of the clinical findings of OSSN: irregular, thick- ened limbal, corneal and conjunctival ep- ithelium, and neovascularization. The abnormal epithelium typically arises from the limbus and can progress centrally over the cornea or posteriorly over the conjunc- tiva or in both directions. An atypical "pterygium" in an elderly patient should alert one to the diagnosis of OSSN. Many new adjunct treatments are now available to reduce the recurrence and avoid the problem of multiple exci- sions in those cases of recurrence. Mitomycin-C (MMC), 5-fluorouracil (5-FU), and interferon alpha 2b are all adjunctive treatment choices in addition to the stan- dard surgical resection and cryotherapy. In this issue's "Cornea corner of the world," Carol L. Karp, M.D., and Shahzad I. Mian, M.D., share their insights into the manage- ment of OSSN. Edward J. Holland, M.D., cornea editor A gelatinous-appearing ocular surface squamous neoplasia Ocular surface squamous neoplasia in an HIV-positive patient. Note feeder vessels and both papillary and leukoplakic features of the lesion Source (all): Carol L. Karp, M.D. This disease rarely metastasizes, but it can cause severe tissue destruction N ot long ago, the term ocular surface squamous neoplasia (OSSN) was used to include every- thing from simple dyspla- sia to carcinoma in situ to invasive squamous cell carcinoma.1 Before the umbrella term was coined, most corneal specialists labeled the disor- ders as conjunctival intraepithelial neoplasia, but "that term empha- sized that the lesions were pre-can- cer," said Shahzad I. Mian, M.D., associate professor, ophthalmology and visual sciences, Kellogg Eye Cen- ter, University of Michigan Medical School, Ann Arbor. "The advantage of having the simpler umbrella term is that people can use it more fre- quently and don't necessarily have to rely on histopathology as a clini- cal diagnosis." The new terminology covers everything from mild to moderate to invasive, said Carol L. Karp, M.D., professor of clinical ophthalmology, Bascom Palmer Eye Institute, Uni- versity of Miami Miller School of Medicine. "It encompasses the spec- trum of squamous neoplasia that af- fects the conjunctiva." Prevalence is increasing, and OSSN is "the most common non-pigmented ocular tumor" diagnosed today, she said, but it's still rare. OSSN has a rather low incidence (reported as high as 3.5 per 100,000 in areas closer to the equator and as low as 0.02 per 100,000 in areas farther from the equator). "A lot of patients will have com- mon sun-related lesions, like ptery- gia," Dr. Karp said, "but OSSN is malignant." Most OSSN lesions are found around the limbus with prominent feeder blood vessels and a leukoplakia with a keratin plaque covering the lesion, said Dr. Mian. These lesions can also be gelatinous and may be on the cornea with an opaque look, Dr. Karp added. Staining with rose bengal can be helpful in delineating a central lesion, she said. In her southern Florida location, she's even seen lesions that appear on the tarsal conjunctiva. Risk factors for OSSN include ex- posure to sunlight, fair skin/pale iris, human papilloma virus and HIV, cig- arette smoking, chronic contact lens use, and chronic inflammation. "There are non-invasive ways to diagnose OSSN," Dr. Karp said, among them impression cytology, ultra-high resolution optical coher- ence tomography, and confocal microscopy. The gold standard, however, is biopsy, she said. "Bottom line—if you're unsure if it's OSSN or not, biopsy and send out for analysis," she said. The risk of recurrence depends largely on the tumor type, size, and initial therapy, according to Yousef and Finger,2 with rates reported as low as 0% for T1- and T2-staged tu- mors to 50% for T4-staged tumors. The two also recommended treat- ment strategies be affected by tumor staging at presentation. Treatment possibilities Treatments for OSSN include topical medications such as mitomycin-C (MMC), 5-fluorouracil (5-FU), inter- feron, radiotherapy, or surgery. Tra- ditionally, the treatment has been surgical excision, which can result in a "5-10% recurrence rate," Dr. Karp said. "While it works well in the ma- jority of cases, extensive excisions carry the risk of limbal stem cell deficiency, scarring, and double vi- sion." In her approach to treatment, she always offers both surgery and medical options. Surgery is best when the lesion is localized, the diagnosis is in question, the patient will not/can not put in drops, or the patient does not have the funds for the medications. Medical treatment is preferred in diffuse disease where it is difficult to tell where the surgi- cal borders of the lesion are, in cases of recurrent OSSN, and in large or annular tumors where surgical re- moval could lead to limbal stem cell deficiency, or in patients who simply prefer not to undergo a procedure. "Topical medication has the benefit that it can treat the subclinical, invisible disease," Dr. Karp said. She recommended interferon alpha 2b, 5-FU, or MMC to treat these squamous lesions. These med- ications are off label, she said. If the patient is compliant and willing to use drops continuously for several