American Board of Dental Examiners (ADEX) Dental Hygiene Licensing Examination 2025 – 400 Free Practice Questions to Pass the Exam

In the case of nodular melanoma, a characteristic feature is the absence of a radial growth phase. Unlike other forms of melanoma that begin with a horizontal spread of cancer cells within the epidermis before progressing to a deeper invasion, nodular melanoma typically arises as a vertical growth. This means that when nodular melanoma develops, it grows directly downward from the outset, leading to a more aggressive progression and a quicker invasion of the deeper tissues compared to other types.

In contrast, superficial spreading melanoma often exhibits a radial growth phase where it spreads out on the skin's surface before penetrating deeper. Lentigo maligna also begins with a long radial growth phase, typically in sun-exposed areas, while acral lentiginous melanoma, found on non-hairy surfaces of the body, also demonstrates radial growth before entering the vertical phase. Thus, the lack of a radial phase in nodular melanoma is what differentiates it from these other types.