To report a case of diffuse conjunctival melanocytic lesion mimicking conjunctival melanoma and treated by surgical excision and amniotic membrane transplantation.

A 29-year-old man presented with diffuse pigmented lesion on the bulbar conjunctiva in the right eye, which had been present since birth. Circumferential pigmentation was observed in the perilimbal conjunctiva from 4 to 11 o'clock, and slightly elevated, dark brown-colored lesions with multiple small cysts were noted on the superior, inferior, and temporal bulbar conjunctiva. Incisional biopsy was performed from multiple sites to rule out conjunctival melanoma. Histopathologic examination showed small nevus cells and multiple cysts. Under local anesthesia, temporal conjunctival excision and amniotic membrane transplantation were performed. The surgical pathologist confirmed compound nevus. Four weeks after the surgery, full epithelialization was observed over the amniotic membrane. Several lesions were intentionally left during the surgery, and unnoticeable from the frontal view. The patient was satisfied with the surgical result.

In extensive conjunctival pigmented lesion, biopsy should always be performed to rule out melanoma. Temporal conjunctival excision rather than whole lesion excision can be a cosmetically good surgical option for a diffuse conjuntival lesion proven as a benign conjunctival nevus.