Conjunctival tumours in children are nearly always benign, but several features differentiate melanoma from nevus and lymphoma from benign reactive lymphoid hyperplasia (BRLH), researchers say.

In a report in JAMA Ophthalmology, Dr Carol L. Shields and colleagues from Wills Eye Hospital, Thomas Jefferson University, in Philadelphia, provide a detailed analysis of the types and frequencies of 806 conjunctival tumours in 782 children seen between 1975 and 2015.

The five most common specific diagnoses were nevus (61 per cent), BRLH (5 per cent), conjunctivitis with nodule (4 per cent), dermoid (4 per cent), and primary acquired melanosis (3 per cent). Only 27 cases (3 per cent) were malignant (18 melanomas and 9 lymphomas).

Nevus, papilloma, and lymphoma were more common in whites than in African Americans, whereas racial melanosis was more common in African Americans. Dermoid was more common in females, conjunctivitis with nodule in males.

Tumour management included surgical excision (55 per cent), observation (40 per cent), and topical or systemic antibiotics or corticosteroids (4 per cent).

Compared with benign nevus, melanoma had an older age of onset, a greater mean thickness, more often had a tumour base of 10 mm or greater and tumour hemoarrhage, and less often occurred with cysts.

Compared with BRLH, lymphoma more often had diffuse involvement, a location in an inferior quadrant or a superior quadrant, and a mean basal diameter greater than 10 mm.

"These data, from an ocular tertiary referral centre, suggest that conjunctival tumours in children are nearly always benign," the researchers conclude. "The few malignant tumours include melanoma and lymphoma."

In our experience about 1 per cent of cases are malignant, and of epithelial origin, usually associated with other disease

Dr Martin A. Zimmermann-Paiz from Hospital de Ojos y Oídos "Dr Rodolfo Robles V." in Guatemala City, who earlier reviewed 165 cases of conjunctival tumours in children, told: "Conjunctival tumours in children are known to be mostly benign. In our experience about 1 per cent of cases are malignant, and of epithelial origin, usually associated with other disease."

"In our experience, malignant tumours in children are generally associated with other systemic diseases," he explained. "Patients with immunosuppression or disorders of DNA repair, such as xeroderma pigmentosum, should be carefully followed up because malignant epithelial lesions are more frequently found in these patients."

Dr Shields did not respond to a request for comments.