Clinical characterization of primary acquired melanosis.

Purpose: Primary acquired melanosis (PAM) is the name applied to flat, speckled, brown lesions of the conjunctival epithelium. Because there have been reports that many of these lesions progress to melanoma, biopsy of all PAM lesions, regardless of size, is recommended. This study was undertaken to determine the prevalence of PAM, provide a clinical description of the condition, and determine which factors are associated with its presence.

Methods: One hundred forty-six consecutive patients, who were outpatients at a corneal and external diseases service, who had no known non-European ancestry, and who were older than 10 years of age underwent careful slit lamp examination.

Results: The prevalence of PAM in the study population was 36%. Contrary to earlier reports, PAM is prevalent in young adults as well as in older patients. The presence of PAM was associated with southern European ancestry (P = 0.01), dark brown hair (P = 0.01), facial nevi (P = 0.03), pingueculae or pterygia (P = 0.01), hypertension (P = 0.02), cigarette smoking (P = 0.02), and the absence of ocular surface disease (P = 0.02).

Conclusions: Because PAM is common, its transformation to conjunctival melanoma must be extremely rare, and biopsy of all PAM lesions is unwarranted. In the absence of known clinical risk factors for progression to melanoma, interim recommendations are made to perform biopsy only of those lesions that are widespread, large, thickened, dark, palpebral, unusually vascular, or progressive.