Balloon cell naevus of the conjunctiva: clinicopathological features and management.

A 7-year-old Caucasian girl presented with a pigmented lesion on the left bulbar conjunctiva that increased in size from 1 mm to 4 mm over a 12-month period. She underwent excision biopsy and reconstruction of the ocular surface with amniotic membrane graft. Histopathology showed the naevus was composed of somewhat swollen naevus cells with clear cytoplasm and central nucleus. These vacuolated naevus cells were approximately 40 µm in diameter. Over 90% of the cells in the naevus were composed of these swollen cells. Immunohistochemical staining was positive for S100 and Melan-A. This case illustrates that balloon cells may be observed in conjunctival naevi at a previously unreported pre-pubescent age. Awareness of ballon cell naevus is important to avoid clinical and histological pitfalls in diagnosis.