Muco-epidermoid variant of Ocular surface squamous neoplasia
Dr. Samyak Gupta, Dr. Prabhat Nangia, Dr. Sarang Lambat, Dr. Vinay Nangia
559, Suraj Eye Institute, Nagpur.
A male, 72 years of age, came with a complaint of redness and irritation in left eye since 3 years. He was a known case of Diabetes mellitus and Ulcerative colitis. His best corrected visual acuity(BCVA) was 6/9 P, N6 in right eye (OD) and 6/9, N6 in left eye (OS). Anterior segment examination showed immature cataract in the both eyes and left side showed a mass temporally adjacent to the limbus. Mass was fixed to the limbus from 4 to 5 ‘o’ clock and measured approximately 3 x 3 cm. Mass was mobile over conjunctiva and its surface was seen to stain with rose bengal. Feeder vessels were seen to supply the mass. Intraocular pressure recorded by Goldmann applanation tonometer was 24 mmHg in OD and 20 mmHg in OS. Fundus examination in both eyes was within normal limits.
Patient was diagnosed as a case of Ocular surface squamous neoplasia(OSSN). He was advised to undergo excision of the mass with cryotherapy. He underwent the procedure which was done with a no-touch technique and a 4 mm clear margin was removed. Amniotic membrane transplantation was done to cover the area of tissue defect created. Excised tissue was sent for histopathological analysis. Histopathological examination confirmed the lesion to be a OSSN of the mucoepidermoid variant.
Ocular surface squamous neoplasia(OSSN) is a term coined to denote the wide spectrum of dysplastic changes involving epithelium of conjunctiva, cornea and limbus.
OSSN has 3 grades viz. Benign dysplasia, pre-invasive OSSN and invasive OSSN. Risk factors include exposure to UV-B light and Human papilloma virus. Xeroderma pigmentosa and human immune-deficiency virus(HIV) patients develop OSSN at an earlier age. Muco-epidermoid OSSN is a very rare variant but is known to be significantly more aggressive than other variants.
Typical presentation of OSSN is of a slightly elevated lesion and has tufts of vessels known as sentinel vessels. Appearance of OSSN on anterior segment OCT is very typical characterized by hyperreflectivity, abrupt transition from normal to abnormal tissue and epithelial thickening. AS-OCT aids in differentiating OSSN from other benign lesions like pterygium and other epibulbar lesions. It also gives an exact extent of margins of the lesion and is also helpful in identifying recurrence post-operatively.
Treatment options include topical chemotherapy with Mitomycin C or Interferon α-2b, tumour excision with cryotherapy and amniotic membrane transplantation. No touch technique during OSSN avoids direct manipulation of the tissue and prevents tumor seeding. Cryotherapy during surgery causes ischemic necrosis and destroys any residual tumor beyond the surgical margin of excision, thereby reducing recurrence. Topical chemotherapy decreases the risk of limbal stem cell deficiency, and removes the need for clear tumor margins as it treats the entire ocular surface, including the potentially dysplastic cells. Agents include Mitomycin C, 5-Fluorouracil, Interferon alpha2b and Pegylated interferon alpha2b.
In our case, patient had 1-2 clock hours of lesion with typical features of OSSN. Therefore we decided to do a local excision with no-touch technique and 4 mm clear margins. Intraoperative cryotherapy was done to the residual conjunctiva beyond excised margins. On histopathology, the lesion was confirmed to be OSSN of the muco-epidermoid variant and margins were noted to be positive for tumor cells. Prompt referral to an oncologist and initiation of topical interferon alpha2b post-operatively may have been instrumental in preventing any recurrence even after 6 months to 1 year of surgery. Amniotic membrane transplantation simultaneously during surgery was effective for reconstruction of tissue defect.
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Dr Prabhat Nangia
DNB, FICO, FMRF, FAICO
Department of Cornea and Ocular Surface
Suraj eye Institute
Email – firstname.lastname@example.org