While sharing some irregular features (the "ABCDEs"), an atypical nevus is distinguished from melanoma by a lack of significant or rapid change over time, which is a key warning sign for melanoma.
This is a benign mole with a distinct, uniform steel-blue or grey color, lacking the variegation of color (multiple shades of brown/black/red) often seen in a melanoma.
This mole is present at or near birth, a historical fact that distinguishes it from melanoma, which is typically acquired later in life.
The key differentiator is the 'dimple sign'—squeezing a dermatofibroma causes it to retract inward, whereas a nodular melanoma would protrude.
This lesion is characterized by its very dark, reticulated (net-like) pattern of pigmentation on a pale background, resembling a spot of ink, which is a different morphology from most melanomas.
This is a benign, raised, often flesh-colored and dome-shaped mole that is typically soft and lacks the firm, irregular, and pigmented features of nodular melanoma.
This is a completely flat, uniformly pigmented brown or black macule, lacking the elevation, irregular borders, or color variation that would suggest melanoma.
A simple lentigo (freckle) is a small, well-demarcated, uniformly colored macule, whereas a lentigo maligna (a type of melanoma in situ) is a larger, slowly enlarging patch with color variegation.
This is a form of melanoma in situ, but it is distinguished from invasive lentigo maligna melanoma by being completely flat, without any palpable or nodular component.
This is, by definition, early melanoma, but it is distinguished from invasive melanoma because the malignant cells are confined entirely to the epidermis and have not broken through the basement membrane.
This is a 'mole within a mole,' a background café-au-lait patch with multiple darker spots inside it, a unique pattern not seen in a typical primary melanoma.
This precancerous lesion has a characteristic rough, "sandpaper" texture and occurs on sun-damaged skin, unlike the smoother surface of most early melanomas.
Distinguished by classic BCC features like a pearly, rolled border and fine blood vessels (telangiectasias) on its surface, which are not typical of melanoma.
This is a very firm, plaque-like, or nodular tumor that is fixed to deeper tissues, feeling much more indurated than a typical melanoma.
This benign tumor is characteristically very hard or rock-like on palpation due to calcification, a feature not found in melanoma.
This benign sweat gland tumor is often found on the palms or soles and may have a moist or warty surface, unlike melanoma.
This benign vascular growth is distinguished by its rapid development, bright red color, and tendency to bleed profusely with minor trauma—features that separate it from an amelanotic (non-pigmented) melanoma.
The key sign is its 'stuck-on' appearance and greasy or warty texture; it can often be gently picked or scraped off, which is not possible with a melanoma.
Often called a "benign melanoma of childhood," this typically presents as a rapidly growing, symmetric, pink or reddish dome-shaped papule, most commonly in a child or young adult.
This benign vascular lesion will suddenly turn dark purple or black due to a blood clot, but it will typically resolve on its own and lacks the progressive growth of a melanoma.
