Primary acquired melanosis (PAM) without atypia/WHO low-grade conjunctival melanocytic intraepithelial lesion over areas of oculodermal melanocytosis.

An elderly white man with a history of left oculodermal melanocytosis presented with new onset brown pigmentation of the left bulbar and inferior tarsal conjunctiva. The bulbar conjunctival pigmentation was at the level of the conjunctival epithelium and was overlying areas of typical slate-grey scleral pigmentation characteristic of oculodermal melanocytosis. Both areas of new pigmentation were biopsied. The bulbar conjunctiva revealed primary acquired melanosis (PAM) without atypia with increased melanin production and the tarsal conjunctival biopsy showed PAM without atypia sine pigmentio overlying areas of substantia propria spindle-shaped heavily pigmented melanocytes of oculodermal melanocytosis. The case report examines the relationship between the epithelial and substantia propria melanocytes and correlates the findings with what is known about this association from the dermatopathology literature. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.