Abstract
Background: Ocular surface squamous neoplasia (OSSN) is a unifying term used to describe conjunctival intra-epithelial neoplasia, squamous cell carcinoma in situ and invasive squamous cell carcinoma.Aim: The aim of this article was to describe the demographics, clinical features, pathogenesis and risk factors of OSSN.Method: A literature search was conducted using the search criteria ‘ocular surface squamous neoplasia’, ‘diagnosis’, ‘epidemiology’, ‘pathogenesis’ and ‘risk factors’.Results: Ocular surface squamous neoplasia is the most common ocular tumour, with incidence rates ranging from 0.01 to 3.4 per 100 000 persons/year. There are two main patterns of disease presentation: older white males in temperate climates where human immunodeficiency virus (HIV) and human papilloma virus (HPV) are not associated; and a younger patient population in tropical climates where HIV and HPV are more prevalent. The pathogenesis primarily revolves around ultraviolet B exposure and HPV infection that cause genetic mutations and uncontrolled cellular proliferation, whilst HIV infection and vitamin A impair tumour surveillance mechanisms. Ocular surface squamous neoplasia is first suspected clinically before formal confirmation of the diagnosis. Morphologically, it can be divided into three groups: placoid, nodular and diffuse. Placoid lesions can further be sub-divided into gelatinous, leukoplakic and papilliform lesions. Nodular lesions have the poorest prognosis, with the highest risk of metastasis and recurrence.Conclusion: Ocular surface squamous neoplasia is a common ocular tumour associated with ultraviolet radiation, HPV and HIV infection. The pathogenesis revolves around acquired genetic mutations, unregulated cellular proliferation and impaired tumour surveillance mechanisms.
Highlights
Squamous cell carcinoma of conjunctiva was first described by Von Graefe in 1860
Owing to inconsistency in terminology used in the literature, Lee and Hirst coined the term ‘ocular surface squamous neoplasia’ (OSSN) in 1995 to describe all conjunctival squamous tumours.[1]
Once the basement membrane is breached and the substantia propria of the conjunctiva is involved, a diagnosis is made of invasive squamous cell carcinoma.[1]
Summary
Owing to inconsistency in terminology used in the literature, Lee and Hirst coined the term ‘ocular surface squamous neoplasia’ (OSSN) in 1995 to describe all conjunctival squamous tumours.[1] These include conjunctival intra-epithelial neoplasia (CIN), squamous cell carcinoma in situ and invasive squamous cell carcinoma. Conjunctival intra-epithelial neoplasia lesions are characterised by dysplastic cells that progressively occupy the conjunctival epithelium from the basal layer. When the entire epithelium consists of dysplastic cells with an intact basement membrane, the lesion is called squamous cell carcinoma in situ. Once the basement membrane is breached and the substantia propria of the conjunctiva is involved, a diagnosis is made of invasive squamous cell carcinoma.[1]. Ocular surface squamous neoplasia (OSSN) is a unifying term used to describe conjunctival intra-epithelial neoplasia, squamous cell carcinoma in situ and invasive squamous cell carcinoma
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