OSSN: Exam Clues and Management
Master ocular surface squamous neoplasia (OSSN) with NBEO and OKAP clues on presentation, risk factors, workup and management.
A classic appearance of ocular surface squamous neoplasia is:
OSSN in 30 Seconds
Ocular surface squamous neoplasia, or OSSN, encompasses conjunctival and corneal intraepithelial neoplasia through invasive squamous cell carcinoma. It usually presents at the limbus and can mimic benign surface disease. NBEO and OKAP test its appearance, risk factors, diagnostic approach and treatment.
Clinical Features
- Appearance: gelatinous, papilliform or leukoplakic limbal lesion. Exam relevance: leukoplakia and a gelatinous limbal mass favor OSSN.
- Feeder vessels: prominent vascularity may supply the lesion. Exam relevance: feeder vessels raise suspicion for neoplasia.
- Location: interpalpebral limbus, the ultraviolet-exposed zone. Exam relevance: this location is a high-yield diagnostic clue.
- Corneal component: grayish avascular epithelial extension onto the cornea. Exam relevance: corneal extension supports OSSN over simple conjunctival degeneration.
- Staining: rose bengal or lissamine green highlights abnormal epithelium. Exam relevance: surface staining helps define epithelial involvement.
- Anterior segment OCT: shows a thickened hyperreflective epithelium with an abrupt transition from normal to abnormal tissue. Exam relevance: this AS-OCT pattern is increasingly tested.
Risk Factors and Workup
- Ultraviolet light exposure is the major risk factor. Exam relevance: select ultraviolet exposure when asked for the leading association.
- Human papillomavirus has an association in some cases. Exam relevance: HPV is associated but ultraviolet exposure remains the key risk factor.
- Immunosuppression, including HIV, occurs especially in younger patients. Exam relevance: young patients with OSSN warrant evaluation for HIV.
- Fair skin and older age increase risk. Exam relevance: the classic patient is older with significant ultraviolet exposure.
- Diagnosis: histopathology after no-touch excisional biopsy is the gold standard. High-resolution OCT and impression cytology are useful adjuncts. Exam relevance: histopathology confirms the diagnosis.
4 Facts Exams Always Ask
- A gelatinous or leukoplakic limbal lesion with feeder vessels is a classic OSSN presentation.
- Ultraviolet light is the main risk factor. HPV and immunosuppression are associated, and OSSN in a young patient should prompt HIV testing.
- Management includes no-touch excisional biopsy with cryotherapy, or topical chemotherapy such as interferon alfa-2b, 5-fluorouracil or mitomycin C.
- Most OSSN grows slowly and invades locally. Metastasis is rare, though local recurrence can occur and requires long-term follow-up.
The Classic Trap
Do not label every limbal lesion as pterygium or pinguecula. OSSN can also resemble papilloma or pseudoepitheliomatous hyperplasia. A gelatinous or leukoplakic lesion at the interpalpebral limbus with feeder vessels should raise concern for OSSN. In a young patient, evaluate for immunosuppression or HIV.
Clinical Pearl
OSSN in a young or middle-aged patient without heavy ultraviolet exposure should prompt HIV testing. Immunosuppression is a recognized risk factor and disease may be more aggressive in these patients. Topical interferon alfa-2b, 5-fluorouracil or mitomycin C is a widely used alternative or adjunct to excision. Metastasis is rare but the tumor is locally invasive, and local recurrence warrants long-term follow-up.
Checkpoint 1
Which risk factor is strongly associated with ocular surface squamous neoplasia?
Checkpoint 2
Which risk factor is most strongly implicated in the development of ocular surface squamous neoplasia (OSSN) in sub-Saharan Africa?
An adult has a vascularized gelatinous lesion at the interpalpebral limbus with visible feeder vessels and a grayish epithelial extension onto the cornea, enlarging over several months. OSSN is strongly suspected and excisional biopsy is planned. During the no-touch excision, where is cryotherapy most commonly applied?
During surgical excision of OSSN, cryotherapy is commonly applied to:
Sources & Publisher Info
References
- American Academy of Ophthalmology. BCSC Section 4: Ophthalmic Pathology and Intraocular Tumors.
- American Academy of Ophthalmology. BCSC Section 8: External Disease and Cornea.
- Shields CL, Shields JA. Clinical Ocular Oncology.
- American Academy of Ophthalmology. EyeWiki: Ocular Surface Squamous Neoplasia.
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