Comparison of histologic patterns of four major subtypes of melanoma

	Superficial spreading melanoma	Lentigo maligna melanoma	Acral lentiginous melanoma	Nodular melanoma
Pattern of RGP	Diffuse pagetoid	Lentiginous	Lentiginous	Absent
Dominant cell type in RGP	Epithelioid	Epithelioid, spindle, and uncommonly dendritic	Spindle, epithelioid, or dendritic	Not applicable
Epidermis of RGP	Normal to hyperplastic	Atrophic	Hyperplastic	Not applicable
Dominant cell type of VGP	Epithelioid	Spindle and epithelioid	Spindle and epithelioid	Epithelioid
Desmoplasia	Rare	Common	Common	Uncommon
Neurotropism	Rare	Common	Common	Uncommon
Frequency of regression	Often partial regression	Common	Variable	Uncommon

RGP: radial growth phase; VGP: vertical growth phase.

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