Clark et al. (1) defined four major histogenetic types of melanoma based largely on the growth pattern of their intraepithelial portions. These include superficial spreading melanoma (SSM), nodular melanoma (NM), lentigo maligna melanoma (LMM), and acral lentiginous melanoma (ALM). This classification has been challenged on the grounds that these types of melanoma have a similar prognosis when matched for sex, thickness, and site and that many of the characteristics of each type are, in fact, secondary to the site of the neoplasm or caused by secondary changes such as solar elastosis (2). Although there is general agreement that the Clark classification has neither independent prognostic value nor diagnostic relevance, the Clark nomenclature continues to be widely used in clinical practice. It also is entrenched in the medical literature regarding melanoma and correlates with the epidemiology of the disease. The histopathologic presentations of the four major histogenetic types of melanoma are important because they characterize the important microscopic features of melanoma on the major anatomic sites involved by melanoma, for example, LMM on the head and neck region, SSM on the back and legs, and ALM on the sole and nail unit. ALM has a molecular footprint that is distinctive and suggests a pathogenetic difference from melanomas on other anatomic sites (3).
Was this article helpful?
Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.