[Spontaneous regression of primary acquired melanosis of the conjunctiva: a case report].

A 75-year-old female patient was diagnosed with primary acquired melanosis (PAM) of the conjunctiva in 2004. The patient voluntarily chose not to undergo any pharmacological or surgical interventions and only received follow-up observation. During a follow-up visit in 2021, a significant reduction in conjunctival melanin pigmentation was found. Anterior segment optical coherence tomography revealed a marked decrease in the high reflectivity of the corneal epithelial cell layer and a reduction in the highly reflective melanin granules within the corneal epithelium. In vivo confocal microscopy showed a decrease in the oval, short spindle-shaped, highly reflective melanin granules within the corneal epithelium compared to previous examinations, and these granules had not penetrated the basement membrane. These examination results collectively confirmed the reduction in conjunctival melanin pigmentation in the patient.