Let's break this down algorithmically.
Unilateral discharge in a patient >30 years warrants a mammography. Mammography for this patient was normal.
Next step should be to get a prolactin level, but the prompt didn't specify, so let's assume it was normal.
Given a normal mammography and presumed normal prolactin level, physiologic discharge would be the most likely diagnosis.
submitted by โstep_prep5(246)
https://step-prep.org/tutoring/