Clinicopathologic Correlation in Melanocytic Lesions

The majority of melanocytic lesions can be diagnosed with ease by a pathologist; however, a number of cases are histopathologically challenging and have the potential for diagnostic error. In addition to the gross morphologic features, clinical factors that should be considered in the histopathologic evaluation and final diagnosis of these lesions include the age of the patient, the site of the lesion, the presence of an underlying skin condition, as well as history of pregnancy, trauma, or UV irradiation. For instance, the incidence of malignant melanoma increases with age, making this diagnosis highly unlikely in young children. Lentiginous proliferation of melanocytes in conjunction with cytologic atypia is not uncommon in congenital nevi, or nevi of special sites, thereby causing the potential for misdiagnosis of these lesions as malignant melanoma when the clinical history is omitted. Clinical information not only increases the level of diagnostic confidence of the pathologist, regardless of their level of expertise, but it also changes the histopathologic diagnosis in a number of cases. This chapter will focus on a number of scenarios where clinicopathologic correlation is critical in accurately diagnosing challenging melanocytic lesions.