Relationship between Conjunctival Intraepithelial Dendritic Melanocytes and Nevocytes.

Area of Science:

• Ophthalmology
• Dermatology
• Cell Biology

Background:

• Primary acquired melanosis (PAM) is a rare condition characterized by melanocyte proliferation.
• The transformation of melanocytes into nevocytes in adult ocular lesions is not well understood.

Observation:

• A 52-year-old male presented with a 7-month history of a flat, pigmented perilimbal-epibulbar lesion.
• Microscopic examination revealed intraepithelial dendritic melanocytes without atypia, consistent with PAM.
• Additionally, intraepithelial and subepithelial nevocytic nests were observed, expressing MART-1, HMB-45, and SOX-10, and were negative for Ki-67.

Findings:

• The key finding was the presence of dendritic melanocytes undergoing transformation into rounded nevocytes.
• This cellular transition suggests a potential pathway from atypical melanocytes to benign nevus formation within the conjunctiva.
• Immunohistochemistry confirmed the melanocytic origin and lack of significant proliferation markers.

Implications:

• This case challenges the traditional view of PAM solely as a premalignant condition.
• It suggests that conjunctival melanocytes can acquire nevomelanocytic characteristics in adulthood.
• The findings have implications for understanding melanocytic nevi development and the biologic spectrum of conjunctival pigmented lesions.