Melanoma Diagnosis in the Mihm Era-And Beyond

Abstract

During the illustrious career of Martin C. Mihm Jr., MD, the diagnosis of melanoma underwent significant changes, to which he made many contributions. In early descriptions, melanomas were fungating tumor masses that were obviously malignant, and highly lethal. In seminal work by Dr. Mihm and his mentor, Wallace H. Clark, Jr., MD, the early phases of development of these neoplasms were recognized and distinguished from the more advanced disease. It was generally believed that the early stage of melanoma, termed radial growth phase (RGP) and characterized by absence of vertical growth phase (VGP) and by favorable microstaging attributes could be recognized, excised, and cured, thus preventing the development of advanced disease. However, strenuous efforts in this direction over several decades have resulted in little or no change in mortality, leading to the recognition that many of these neoplasms, at least, may not be true biological malignancies, and to the conclusion that overdiagnosis commonly occurs in this disease, which is defined as representing diagnosis as melanoma of a neoplasm that would not have had the capacity to cause death or symptoms in the lifetime of the host. Although there may be other subsets of neoplasms in this category, an important category of overdiagnosis in melanomas is concentrated in T1a melanomas that lack VGP. If these neoplasms can be recognized with sensitive and specific criteria, which may already be available, changes in terminology may be appropriate, recognizing that some of them may have low malignant potential, whereas others may have no capacity at all for metastasis and may not warrant the use of the term "melanoma."

Keywords: diagnosis; dysplastic nevi; history; melanoma; overdiagnosis; vertical growth phase.