Comparison of the classification by microscopic level (stage) of malignant melanoma by three independent groups of pathologists.

The ability of groups of pathologists to classify and stage malignant melanoma varies with their familiarity with the new nomenclature proposed for that process. Primary lesions of malignant melanoma from 79 patients were independently examined and classified by community pathologists, university pathologists, and a referee pathologist all without access to each others diagnoses. The diagnoses of these groups were compared for agreement in variety of melanoma as well as depth of dermal penetration (stage or level). Greatest success (agreement with the referee) of both the community pathologists and the university pathologists was achieved when assessment of level of invasion (+/- 1) of the referee was compared (community pathologists = 94% +/- 12% agreement, university pathologists = 99% +/- 2% agreement). Our survey demonstrates that only a relatively small number of community pathologists (23%) employ the new nomenclature, but they do so with a facility equal to that of the university pathologists. Based upon this study and our continuing experiences, we recommend the review of all primary lesions of malignant melanoma by a pathologist or group experienced in the diagnosis and microscopic staging of the disease.