ISOLATED LICHEN PLANUS OF THE CONJUNCTIVA WITH ASSOCIATED BOWEN'S DISEASE: A CASE REPORT

Bowen's disease is an intraepithelial neoplasm involving the squamous epithelium, commonly occuring in the genital region. Rarely, it is also observed at skin in other anatomical location. Lichen planus is chronic dermatoses, which is commonly observed in the extremities and mucosa. In lichen planus ,there will be dense inflammatory infiltrate in the sub- epidermal zone. Very rarely, Lichen planus involving the sub mucosa can undergo malignant transformation. Co-existing isolated lichen planus with the Bowen's involving the conjunctiva is a very rare event. KEYWORDS: Bowen's disease conjunctiva, isolated lichen planus in the conjunctiva. INTRODUCTION: Most of the carcinomas originate as an insitu lesion before becoming an invasive and metastasing lesion. The in situ lesions that occur in the squamous epithelium especially involving the genitals are Bowen's disease, Bowen's papillosis and Erythroplakia of Queyrat. Here with a report on isolated lichen planus with associated Bowen's disease involving the left conjunctiva near the limbus is being presented. Pizzarello and Jakobiec1 proposed designating intraepithelial tumor as conjunctival intraepithelial neoplasia (CIN) and classified the tumor into two types; mild dysplasia and severe dysplasia. In mild dysplasia, dysplastic cells occupy less than half the conjunctival epithelium and in severe dysplasia, more than half or the entire layer. 1 The World Health Organization (WHO) classifies carcinoma insitu with dysplasia and actinic keratosis as a CIN. 2 When intraepithelial dysplastic cells, even partially, invade the basement membrane and infiltrate the sub epithelium of the conjunctiva, the condition is called squamous cell carcinoma (SCC). Conjunctival intraepithelial neoplasia and SCC are histopathologically well-defined conditions. However, it is difficult to determine the grading of dysplasia by clinical morphologic findings. Conjunctival squamous cell carcinoma (intraepithelial and invasive) is the most common conjunctival malignancy in the United States. 3, 4 The incidence of this neoplasm is between 1 and 2.8 per 100 000 people per year and varies in different geographic locations. 5 Epidemiological studies have shown that ultraviolet B radiation (290-320 nm) may be important in its pathophysiology.6, 7 Ultraviolet B induced point mutations in the p53 tumour suppressor gene have been reported in other squamous cell carcinomas.8 Human papillomavirus (HPV) types 16 and 18 may also be important in tumour development. 9- 14 Intraepithelial squamous carcinoma (also known as conjunctival intraepithelial neoplasia, previously known as Bowen's disease) and invasive squamous cell carcinoma of the conjunctiva are histologically differentiated according to the invasion of epithelial basement membrane. In invasive squamous cell carcinoma cells infiltrate through the basement membrane and invade the substantia propria.3 Although intraepithelial squamous carcinoma may progress to invasive squamous cell carcinoma, the former lesions are localised in the epithelium. 3,4 Clinically these tumours most