Non-Melanocytic Melanoma Mimics
These include lesions which contain melanin pigment, but are not melanocyte derived. Any questionable lesion should be biopsied to confirm the diagnosis.
Pigmented Basal Cell Carcinoma
Pigmented basal cell carcinoma contains melanin pigment but is otherwise equivalent to nodular basal cell carcinoma. The amount of melanin and its distribution is variable. Pigmented basal cell carcinoma can be mostly pink, with focal blue to gray pigment or jet black. The surface has a pearl-like quality but may be ulcerated. The appearance may suggest nodular melanoma.
Seborrheic keratoses are benign keratinocyte tumors which also contain varying amounts melanin pigment. Pigmentation can be uneven and asymmetric within a single lesion. Seborrheic keratoses typically appear after age 30 and can grow quite rapidly. Lesions vary from flat to verrucous, and are white to pink to jet black. Flat seborrheic keratoses may suggest lentigo maligna. Raised lesions may suggest superficial spreading melanoma.
Spreading Pigmented Actinic Keratosis
Spreading pigmented actinic keratosis displays fine reticulated pigmentation and thin scale. Lesions appear on sun-damaged skin and simulate lentigo maligna melanoma.
Vascular mimics of melanoma
Mature hemangiomas are often dark purple in color and can mimic nodular melanoma. Solitary angiokeratoma can be black to red. Trauma such as friction injury to the heel (talon noir) or injury to a nail unit may produce hemorrhage. Hemosiderin may be present in these lesions suggesting melanin pigment.
Dermatofibroma is a benign dermal lesion typically found on the lower leg. Dermatofibromas often contain hemosiderin, occasionally itch or are tender, and can resemble melanoma.