Melanocytic nevi and melanoma: overlapping criteria—the degree is the key

Gross and microscopic criteria are morphologic and thus subjectivity abounds for the pathologist in the diagnosis of benign and malignant melanocytic proliferations [1]. The state-of-the-art criteria, often touted to be definitive, delineates between benign and malignant conditions clinically and histopathologically. This issue becomes murky, however, when the same criteria, on occasion, are present in both benign and malignant entities. This twist of fate is commonly referred to as overlapping criteria. This is exemplified frequently in benign melanocytic proliferations, i.e., melanocytic nevus and its variants (so-called combined nevus, Spitz’s nevus, juvenile melanoma, dysplastic nevus, atypical nevus, nevus with architectural disorder and sever/moderate cytologic atypia, deep penetrating nevus, Reed’s nevus, spindle-cell tumor, pre-melanoma, borderline melanoma, and recurrent/persistent melanocytic nevus, all of which are nothing more than a benign melanocytic nevus with findings focal common to those of the infamous melanoma. Overlapping criteria in benign and malignant melanocytic proliferations are well known and expected findings [1-3]. Because of the confusion that overlapping criteria create, it is essential to separate those proliferations truly benign from those that are in fact malignant. Furthermore, it is important, if not imperative, to recognize the degree of criteria, i.e., mild, moderate or extensive. In other words, is the criterion or criteria, an occasional finding, focal, isolated, or diffuse? What is the degree of criteria? Is it just happenstance, and does it matter? This is the question. The assessment of the degree of criteria is of the essence in order to arrive at an accurate diagnosis and avoid a misdiagnosis.