When an unusual spot appears on the skin, the possibility of skin cancer is often the first concern. Early detection is the most important factor for improving outcomes. Amelanotic melanoma (AM) is a specific type of skin malignancy that lacks the typical dark color associated with melanoma. This absence of pigment leads to questions about its physical characteristics, specifically how it behaves when pressure is applied, which is a common at-home test.
Defining Amelanotic Melanoma
Melanoma is a serious form of skin cancer that develops in melanocytes, the cells responsible for producing the pigment melanin. Amelanotic melanoma (AM) is a variant where malignant melanocytes produce very little or no melanin, which gives most melanomas their dark appearance. The term “amelanotic” literally means “without melanin,” making the lesion difficult to recognize using traditional visual cues.
AM accounts for approximately 2% to 20% of all melanoma cases. Because the typical dark color is absent, these lesions often appear pink, red, reddish-brown, skin-colored, or clear spots. Their non-pigmented nature means they can easily be mistaken for benign growths, such as a cyst or a scar, often leading to a delayed diagnosis.
What Blanching Indicates in Skin Lesions
Pressing on a red or pink skin lesion to see if it blanches, or temporarily turns pale, is a technique called diascopy. This maneuver determines the cause of the redness within the lesion. Blanching occurs when pressure temporarily forces the blood out of the superficial capillaries within the skin.
If a lesion is red because the blood vessels near the surface are dilated, such as with an inflammatory rash, it will blanch. The redness returns quickly once pressure is released. Conversely, a red lesion that does not lighten under pressure indicates the redness is caused by blood outside the vessels, like a bruise, or a solid, non-vascular mass.
How Amelanotic Melanoma Responds to Pressure
The question of whether amelanotic melanoma blanches when pressed is generally answered with a “no.” The lesion is a solid, malignant mass of tumor cells (a neoplasm). Applying pressure to this solid tissue does not displace the tumor itself.
The lesion may appear red or pink due to inflammation and increased blood vessel growth necessary to feed the cancer. This vascular supply is often deeper or structurally different from the superficial capillaries of a benign vascular lesion. Therefore, the redness is typically fixed, and the lesion will not fully lighten when pressed firmly.
The non-blanching characteristic of a red or pink lesion should immediately raise suspicion in clinical practice. This inability to blanch helps differentiate AM from common vascular lesions like cherry angiomas, which readily blanch. The clinical rule remains that AM presents as a non-blanching, firm, and often raised lesion, underscoring the need for professional evaluation of any new or changing non-pigmented spot.
Recognition Clues for Non-Pigmented Skin Cancer
Since the traditional ABCDE criteria (Asymmetry, Border irregularity, Color variation, and Diameter) rely heavily on pigment, alternative features are used to identify amelanotic melanoma. Clinicians often look for the EFG criteria: Elevated, Firm, and Growing. These characteristics are highly suggestive of a nodular or rapidly evolving tumor, as the elevated and firm nature indicates a concerning depth of growth.
The most critical clue is Evolution, or change over time, which applies to both pigmented and non-pigmented melanomas. Any new or existing pink, red, or skin-colored spot that is changing rapidly in size, shape, or texture warrants urgent medical attention. Other suspicious signs include an irregular border, persistent itching, crusting, or a tendency to bleed or ulcerate without injury. These non-pigmented indicators are the most reliable warnings for skin cancer lacking dark color.