Are growth phases exclusive to cutaneous melanoma?

Two growth phases, radial and vertical, are commonly identified in cutaneous melanoma. In the radial growth phase, melanoma appears as an irregular plaque; cells may invade the dermis, but do not form a nodule. In the vertical growth phase, the lesion develops vertically, forming a true tumour.1 Growth phases, generally reputed to be sequential stages of tumour development, are considered to be characteristic of skin melanoma and are not generally recognised in other tumours. However, analysing other skin neoplasms, some analogies can be noted. Squamous cell carcinoma originates in the epidermis as squamous cell carcinoma in situ, which shows a radial growth …