A, PAM without atypia. The basilar layer of the conjunctival epithelium is pigmented. There is no histologic evidence of melanocytic atypia. Note that in the term PAM without atypia the word atypia refers to histologic findings, not to the clinical presentation. B, PAM with atypia. Highly atypical epithelioid melanocytes are present within the epithelium. The patient is at high risk for progression to melanoma.