Ocular leptospirosis as the sole clinical manifestation in a pediatric patient: an atypical case.

Radiation-induced optic neuropathy (RION) is an uncommon but potentially devastating complication of radiotherapy (RT) for intracranial or head and neck tumors. It typically presents with subacute, painless, and irreversible vision loss, with a latency of 3 months to 7 years after RT, averaging around 18 months []. Although the overall incidence is low, it may reach up to 9% in nasal cavity and nasopharyngeal tumors irradiated with doses exceeding 50 Gy []. Nasal mucosal melanoma is a rare and aggressive subtype, accounting for approximately 1.3% of all melanomas []. Due to its proximity to the anterior visual pathways, adjuvant RT in this location carries a significant risk of severe visual toxicity. In this context, the increasing use of immune checkpoint inhibitors (ICIs) in head and neck malignancies poses an additional diagnostic challenge in patients presenting with acute vision loss, as immune-mediated optic neuropathy may mimic or coexist with RION []. We describe the case of a patient with nasal mucosal melanoma treated with RT and anti-PD1 immunotherapy, who developed progressive bilateral RION culminating in irreversible blindness.