Learning Center > Health Library > Conjunctival Primary Acquired Melanosis. Conjunctival primary acquired melanosis (PAM) is a painless flat brown spot on the eye that might superficially look like a freckle. It changes very slowly over time. It can be found in children and adults and typically occurs on only one eye. Conjunctival PAM is often precancerous and leads to life-threatening malignant melanoma. Conjunctival PAM should be treated with surgery, cryotherapy, or sometimes chemotherapy eye-drops to eradicate it before melanoma develops.