Ocular surface squamous neoplasia – Review of etio-pathogenesis and an update on clinico-pathological diagnosis

Abstract

Ocular surface squamous neoplasia (OSSN) has a varied clinical presentation, the diagnosis of which rests on the histopathological examination of the excised lesion. The term OSSN includes mild dysplasia on one end of the spectrum and invasive squamous cell carcinoma on the other end. This lesion has a multi factorial aetiology with interplay of several factors like exposure to ultraviolet radiation, various chemical carcinogens and viral infections, however role of individual agents is not well understood. With the upsurge of infection with human immunodeficiency virus, a changing trend is seen in the clinical presentation and prognosis of patients of OSSN even in developed countries. Anterior segment optical coherence tomography (OCT) and confocal microscopy, hold promise in in-vivo differentiation of intraepithelial neoplasia from invasive squamous cell carcinoma. Variants of squamous cell carcinoma like Mucoepidermoid carcinoma, spindle cell carcinoma and OSSN associated with HIV infection should be suspected in a case of aggressive clinical presentation of OSSN or with massive and recurrent tumours. Surgery, chemotherapy and immunotherapy are the various treatment modalities which in combination show promising results in aggressive, recurrent and larger tumours.

Histopathological Study of Ocular Surface Squamous Neoplasia in Biopsies Received at Tertiary Care Centre

“…As mentioned by Mittal R et al (18) , invading tumor can have several patterns like cords, strands and clusters of malignant cells in infiltrative manner, broad pushing fronds with expansive pattern can also be seen. Dense collagenous scleral tissue in cases of conjunctival OSSN and Bowman's membrane in corneal OSSN helps limiting the infiltration.…”

“…Degree of nuclear atypia, irrespective of level of epithelial thickness involved can also cause up gradation or down gradation of severity of dysplasia. Mittal R et al (18) also explained in their study that hyperkeratosis and dyskeratosis that is single cell keratinization with the formation of squamous pearls is not a usual feature of intra epithelial lesions.…”

“…Koilocytes are pathognomic of HPV infection. As explained by Mittal R et al (18) , formation of koilocytes decreases with increasing severity of dysplasia, and they are rarely seen in invasive lesions (18) . In our study, none of the cases showed this feature.…”

“…As explained by Mittal R et al (18) , as the lesion progresses from mild to severe dysplasia, the cells differentiate less and less, losing their squamous features until eventually entire epithelium consists of undifferentiated cells. The dysplastic cells show an increase in the size of nuclei, irregular nuclear membrane, hyperchromatic and fine to coarse nuclear chromatin.…”

“…Mild to moderate chronic inflammatory cell infiltration may be observed and can cause inflammatory destruction of epithelial basement membrane. This should not be confused with invasive squamous cell carcinoma, especially in cases of carcinoma in situ as (18) .…”