Amniotic membrane transplantation for recurrent giant melanocytic nevus of conjunctiva

Dear Editor, Melanocytic lesions account for 53% of cases of all conjunctival neoplasms.[1] They can be categorized as following: conjunctival nevi being the most common found in 52% of the cases, melanoma in 25%, primary acquired melanosis (PAM) in 21%, and racial melanosis in 3%.[1] Conjunctival nevus can be congenital or acquired. It usually develops in the first or the second decade of life and presents as a group of small nests of pigmented epithelial cells found in the basal layer of the epithelium. When the patient enters the second to third decade, the pigmented cells progress into the underlying stroma and convert the nevus into compound nevus. In the third and fourth decade, the cells exist in the stroma as subepithelial nevus.[2] Conjunctival nevi can be found mostly near the limbus in the interpalpebral area. Other common locations are the caruncle, semilunar folds, fornix, tarsus, and cornea.[3] Due to the variable nature of the clinical appearance, the diagnosis can be of great difficulty.[4] The malignancy can be suspected in cases of recurrence after prior biopsy, rapid growth, change in shape or color, and unusual location such as the fornix or tarsal conjunctiva.[1] Here, we report a case of giant conjunctival melanocytic nevus which recurred after a prior excision. A 21-year-old male patient was referred to us with complaints of a blackish pigmented conjunctival lesion in the left eye. The lesion was first noticed by his parents at 1 year of age, growing steadily in size. He underwent surgical excision of the lesion elsewhere at five years of age. Following the surgery, few spots persisted which continued to grow and reach the present size. On ocular examination, the visual acuity in both the eyes was 20/20 by Snellen's chart. The intraocular pressure was found to be 11 mmHg and 12 mmHg by Goldman Applanation Tonometry in the right and left eye, respectively. Eyeballs were orthotropic, extraocular movements were free and full, and adnexa was normal. On slit-lamp examination, a hyperpigmented elevated lesion measuring 14 mm × 12 mm was found on the superomedial part of the bulbar conjunctiva of the left eye, encroaching on the limbus and reaching up to the fornix [Figure 1]. Multiple feeder vessels were seen overlying the lesion. There was no pre-auricular lymphadenopathy. The remaining anterior segment and fundus examination were normal. Impression cytology with Papanicolaou stain showed a highly cellular smear with melanocytic cells, with high nuclear-cytoplasmic ratio and abundant diffuse cytoplasmic pigment. Under peribulbar anesthesia, conjunctival peritomy of the surrounding area was performed and then the lesion was excised from the scleral bed in toto. Since the pigmentation extended onto the cornea, absolute alcohol was applied intraoperatively for one minute and the corneal epithelium and superficial stroma were excised with a margin of 2 mm. Special attention was provided in removing all the pigmented areas. The raw scleral bed was measured with calipers and the desired sized amniotic membrane was transplanted and fixed with the help of fibrin glue. Histopathology revealed sheets and nests of nevus cells seen mainly in the stroma and at places in the epithelium. The tumor cells showed a monomorphic oval nucleus with minimal nuclear atypia and cytoplasmic melanin pigment [Figure 2]. Immunohistochemistry for Ki67 was negative. The excised margins and base of the lesion were free of the tumor cells. The final histopathological diagnosis of a congenital melanocytic nevus with atypia was made. Postoperatively, the patient was given moxifloxacin and dexamethasone combination eye drops for one month in tapering doses and advised regular follow-up in view of a recurrent lesion and nuclear atypia. We have been following up on this patient for two years after surgery. There have been no signs of any recurrence [Figure 3].Figure 1: Slit-lamp image showing hyperpigmented lesion measuring 8 mm × 4 mm was found on the medial part of the bulbar conjunctiva of the left eye, encroaching on the peripheral corneaFigure 2: Photomicrographs of (a) Imprint smears show cohesive clusters of melanocytic cells (Pap stain ×100): (b) shows monotonous cells with abundant diffuse cytoplasmic melanin pigment (Pap ×200): (c) Conjunctival biopsy shows sheets and nests of nevus cells seen mainly in the stroma (H&E ×100) (d) and at places in the epithelium (H&E ×200): (e) tumor cells show monomorphic oval nucleus with minimal nuclear atypia and cytoplasmic melanin pigment (H&E ×200): (f) Immunohistochemistry with Ki67 is not increased (IHC Ki67 ×200)Figure 3: Slit-lamp image after 1-month post-surgery showing the integration of the amniotic membrane into the host tissue, with minimal scarringMelanocytic lesions of the conjunctiva can be classified into nevus, racial melanosis, intermediate melanocytic proliferations, and malignant melanoma.[5] The types of melanocytes which are most commonly found are following: the "dendritic," cells found in benign congenital and acquired conjunctival melanosis, "nevus cells" found in subepithelial, junctional and compound nevi, and "fusiform cells," found in melanosis oculi and the nevus of Ota. Most of the conjunctival nevus develop either later in childhood or early adulthood, and so recognized as acquired.[6] The initial goal of treatment in a case of the suspected neoplastic conjunctival lesion is to perform complete excision of the lesion with a tumor-free margin and reconstruction of the bare area to prevent recurrence and ocular surface complications.[7] Excision of a large-sized conjunctival lesion can also be particularly challenging and different types of complications have been noted like scarring, symblepharon, and limbal stem cell deficiency. Larger sized defects may cause unsatisfactory direct closure, scarring formation, and ocular movements restriction.[7] Achieving a good functional and cosmetic appearance ocular surface reconstruction after surgical excision is of utmost importance. Amniotic membrane transplantation (AMT) has been successfully performed to reconstruct conjunctival defects created by the surgical removal of such pigmented tumors.[8] The amniotic membrane contains many growth factors, anti-inflammatory proteins, different types of collagen, laminin, fibronectin and also produces basic fibroblast, hepatocyte, and transforming growth factor (TGF) which promotes epithelization, stimulate fibroblast proliferation and differentiation, inhibits fibrosis, and causes suppression of inflammation and bacterial growth.[9] Conjunctival autografts and mucosal grafts can also be used for the reconstruction of large conjunctival defects but the amniotic membrane has been proved to be superior to them in all the previous published studies.[10] Most importantly, an AMT provides a normal conjunctival phenotype and has more cosmetic benefits over buccal or mucosal grafts.[8] In our case, the conjunctival nevus recurred following a previous incomplete excision. According to the patient, the size had remarkably increased over the last year. So, we performed a wide and delicate excision of the lesion with special attention not to leave any pigmented tissue behind. We did not resect the tenon's capsule, because studies have proved that tenon's capsule helped in conjunctival epithelization. The clinical features like large size, variegated appearance, extension onto the peripheral cornea, and presence of feeder vessels arose the suspicion of melanoma. However, on histopathological examination, the sheets and nests of nevus cells were seen mainly in the basal layer of the epithelium without any radial or pagetoid spread, and immunohistochemistry for Ki67 was also found to be negative which ruled out a melanoma. The patient is on regular follow-up and apart from minimal scarring, no other complication or recurrence has been noted. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.