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.

The Epstein-Barr virus (EBV) is a member of the herpes family of viruses and is very common in humans. EBV is most often associated with infectious mononucleosis. However, it is estimated that 1% of tumors including lymphoproliferative, epithelial and mesenchymal are linked to EBV infection. EBV has a tropism for certain epithelial cells, lymphocytes and myocytes. Like other herpesviruses, EBV has both lytic and latent phases of infection. In the latent form, EBV-encoded genes ensure the survival of the viral genome, allowing it to circumvent the host’s immune surveillance by limited expression of viral proteins and carries with it the risk of neoplastic transformation. Cytologists are likely to encounter EBV-associated malignancies in cytology material but unlike other herpesviruses, EBV does not evoke a viral cytopathic effect. The manifestation of EBV-related tumors is also often variable depending upon the patient’s immune status. Therefore, knowledge of the patient’s EBV status and immune competence (e.g. HIV-infection or transplant-related immunosuppression) combined with the cytomorphology and results of ancillary studies are often all required to make a diagnosis of EBV-associated malignancy. This review discusses the unique cytomorphology and ancillary studies required to diagnose EBV-related neoplasms.