The invention provides a method for diagnosing a melanocytic proliferation in a subject comprising staining a sample of lesional melanocytes with an antibody against soluble adenylyl cyclase (sAC) and interpreting the sAC staining pattern, which is associated with a diagnosis of a melanocytic proliferation. The sAC staining pattern, which is complex, is discriminatory and distinctive according to the nature of the melanocytic proliferation. The sAC staining pattern comprises one or more of dot-like Golgi staining, broad granular Golgi staining, diffuse cytoplasmic staining, nucleolar staining, incomplete granular nuclear staining, and pan-nuclear staining. The method of the invention is particularly useful in confirming or disaffirming a diagnosis reached through conventional histologic examination of a sample. Additionally, the invention provides a kit for use in interpreting melanocytic proliferations.