Collaborative Stage

Note 1: The vertical growth phase (VGP) represents a stage of progression in which invasive melanoma cells have attained the capacity for survival and proliferation in the dermis which may then lead to the formation of an expansile tumor mass. Individual melanoma cells or small clusters of cells invading the superficial dermis do not necessarily represent vertical growth phase. While the presence of VGP is usually obvious in a thick melanoma, in a thin melanoma the minimal definition of VGP is the presence of 1 or more dermal clusters larger than the largest epidermal cluster (tumorigenic VGP) and/or the presence of any mitotic activity in the dermis (mitogenic VGP), either of which indicates the capacity for proliferation in the dermis. The VGP may occur in the presence or absence of an adjacent radial growth phase (RGP), which may be in situ or invasive. RGP is defined as melanoma without VGP. Nodular melanoma exhibits only a vertical growth phase without a radial growth phase; there may be an intraepidermal component above but not (beyond an arbitrary limit of 3 rete ridges) adjacent to the VGP.
Note 2: Record the VGP as recorded in the pathology report. When the VGP is "not identified" registrars should code as absent.

Code	Description
000	No vertical growth phase present Vertical growth phase not identified Vertical growth phase absent
001	Vertical growth phase present
988	Not applicable: Information not collected for this case
998	No histologic exam of primary site
999	Unknown Not stated Not documented in patient record

CS Site-Specific Factor 9
Vertical Growth Phase