## Cutaneous Melanoma Subtypes ### Recognized Subtypes The four major histopathologic subtypes of cutaneous melanoma are: | Subtype | Growth Pattern | Prognosis | Key Feature | | --- | --- | --- | --- | | Superficial Spreading Melanoma (SSM) | Radial then vertical | Intermediate | Most common (70%); horizontal growth phase | | Nodular Melanoma (NM) | Primarily vertical | Worst | No radial growth phase; rapid progression | | Lentigo Maligna Melanoma (LMM) | Radial then vertical | Best | Sun-exposed areas; elderly patients; slow growth | | Acral Lentiginous Melanoma (ALM) | Radial then vertical | Poor | Palms, soles, nail beds; common in darker skin | **Key Point:** These four subtypes account for >95% of cutaneous melanomas and are defined by histologic growth patterns and anatomic location. ### Why Verrucous Melanoma Is Not a Recognized Subtype **High-Yield:** Verrucous melanoma is **not** a standard histopathologic subtype of cutaneous melanoma. It is sometimes used descriptively to refer to a clinically warty or papillary surface appearance, but it is not a distinct subtype in the WHO or AJCC classification. **Clinical Pearl:** Verrucous lesions on the skin are more commonly associated with benign conditions (verrucae, seborrheic keratosis) or other malignancies (verrucous carcinoma of squamous origin), not melanoma. **Warning:** Do not confuse verrucous appearance (clinical morphology) with verrucous melanoma (non-existent subtype). Melanomas may have a verrucous or papillary surface, but this is a descriptive feature, not a subtype classification.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.