In 1977, the staging system of the AJCC was the first to incorporate "microstaging," that is, findings by conventional microscopy such as Clark's levels and Breslow's thicknesses.⁹ Theirs, too, was a four-tier system, although Stage I was divided into IA and IB. The system was formulated in this manner:

Novel, as well, was the placement of distant lymph node metastases in Stage III. That decision resulted in a system in which three of the four stages were related intimately. In short, Stages II, III, and IV all come into being as a result, directly, of the same initiating event, that is, neoplastic cells of melanoma gaining access to the systemic circulation. Because the lymphatic and hematogenous circulations are connected to one another, metastases, irrespective of whether they are termed satellite, in transit, regional, or distant (including visceral), have in common dissemination through vascular channels of both kinds. In this sense, all metastases, no matter where they first manifest themselves or where they are first detected, are distant conceptually.¹⁰ To complicate matters further, the introduction of notions such as "massive" or "fixed" lymph nodes heightened the subjectivity of the system even more, the likes of which had not been seen since the staging system first was brought forth by Ackerman and Del Regato.