“Do not ignore a pigmented lesion,” Dr. Shields advised.
In pediatric cases, the diagnosis is almost always a nevus.
However, in some middle-aged patients, a pigmented lesion could be nevus or something more suspicious, like PAM or melanoma. These patients should be referred to an ocular oncologist for management.
Conjunctival nevus starts at the junction of the epithelium and the stroma, generally as a congenital birthmark that becomes visible in the first decade of life.
“One of the hallmarks of conjunctival nevi is the presence of intralesional cysts seen in about 65% of cases,” Dr. Shields said. “Nevi can be pigmented or nonpigmented, and the nonpigmented lesions often masquerade as other conditions, like episcleritis, scleritis, and lymphoid tumors.
“Cysts are not pathognomonic for nevi,” she added. “They can be found with other tumors, such as mucoepidermoid squamous neoplasia or lymphangioma/lymphangiectasia.”
Most conjunctival nevi occur on the bulbar conjunctiva right at the limbus at 3 or 9 o’clock, according to Dr. Shields.
It is “pretty rare to see a nevus in the fornix or on the tarsus or on the cornea,” she said.
Consider PAM if there is a pigmented lesion in those areas, she advised.
About 15% of conjunctival nevi occur in the caruncle region, and these nevi have fine hairs from the pilosebaceous units emanating through the nevus.
“Keep in mind, melanoma in the caruncle can occur and that’s an ominous location because it tends to grow deep before it is discovered,” Dr. Shields said.
There are several types of nevi, including giant nevus and blue nevus. Giant nevi occupy at least one quadrant on the bulbar surface—and based on size alone, melanoma is considered. Ideally, these should be completely resected.
Blue nevus tends to be deep to Tenon’s fascia with a gray-black appearance.
“Even though it is benign, the dark color imparts a suspicious look and can resemble deep melanoma,” she said. "Flip the lid and check the tarsus to rule out tarsal PAM or melanoma.”
Overall, studies suggest 1 in 300 conjunctival nevi will evolve into melanoma.