Melanoma is a serious form of skin cancer most often recognized by its dark color, a result of the pigment melanin. Amelanotic melanoma presents a significant challenge because it lacks this typical dark coloring, making it difficult to spot for both patients and clinicians. This variant often appears as a pink, red, or skin-colored lesion, easily mistaken for a harmless mole, scar, or other benign condition. The lack of pigment leads to a common question: whether this non-pigmented growth turns white when pressed, a phenomenon known as blanching.
Blanching and Skin Lesions
Blanching is a physical reaction where a red or pink area of skin temporarily turns pale or white under pressure, then quickly returns to its original color once the pressure is removed. This happens because the pressure pushes blood out of the fine, superficial blood vessels, or capillaries, located in the skin’s top layers. Lesions that blanch are typically vascular in nature, meaning their color comes from an accumulation or dilation of blood vessels, such as with cherry angiomas or certain inflammatory rashes.
Amelanotic melanoma generally does not blanch when pressed because it is primarily a solid tumor mass, not a purely vascular phenomenon. The lesion’s reddish or pink appearance is caused by the body’s inflammatory response and the proliferation of tumor cells that are growing deep into the skin layers. While some blood vessel structures may exist within the tumor, the density of the malignant cells prevents the simple displacement of blood that defines true blanching.
Blanching is not a reliable diagnostic indicator for this type of cancer, and relying on this test can lead to a dangerous misdiagnosis. The overall structure of the lesion is characteristic of a solid, firm growth. A lesion’s failure to blanch offers no reassurance that it is benign and should never be used to rule out a melanoma.
What Amelanotic Melanoma Is
Amelanotic melanoma is defined by the absence or near-absence of melanin production by the malignant cells, which removes the most recognizable visual cue of skin cancer. This lack of color means the lesion typically presents as various shades of pink, red, or sometimes a translucent skin-color, occasionally with subtle gray or brownish edges. This makes it a great mimic of many common, harmless skin conditions.
This variant accounts for approximately 2% to 20% of all melanoma cases, making it less common but significantly more challenging to diagnose. The aggressive nature of the tumor, combined with its deceptive appearance, often results in a delayed diagnosis compared to pigmented melanomas. Consequently, it is often not biopsied until it has reached a more advanced stage, meaning the prognosis is often less favorable than for pigmented types.
Identifying Non-Pigmented Skin Lesions
Since the traditional ABCDE criteria for melanoma rely heavily on the Color component, which is missing in this variant, alternative methods are required for identification. The most useful framework for recognizing a potentially dangerous non-pigmented growth is the EFG rule. This acronym focuses on the physical characteristics of the lesion rather than its pigment.
The “E” stands for Elevation, meaning the lesion is raised noticeably above the surrounding skin, suggesting vertical growth into the tissue layers. The “F” represents Firmness, indicating that the lesion feels solid and hard to the touch. This firmness is a key indicator of a dense collection of malignant cells.
The “G” is for Growth, which refers to a rapid or sustained change in size or shape, often over a period of weeks or months. Non-pigmented lesions that are new, growing quickly, and feel firm should be viewed with suspicion. Amelanotic melanoma might also present as a persistent, non-healing sore or a red, dome-shaped nodule that bleeds easily.
When to Seek Medical Attention
Any new or existing skin lesion that is evolving warrants an immediate professional medical evaluation. This is especially true if the lesion is firm, growing rapidly, or if it begins to bleed, crust, or ulcerate. A persistent non-healing area on the skin, even if it appears harmless, should never be ignored.
A dermatologist can perform a detailed examination using a tool called a dermatoscope, which helps visualize structures beneath the skin’s surface that are invisible to the naked eye. If the lesion remains suspicious after this initial physical assessment, the definitive diagnostic step is a biopsy. This procedure removes a sample of the tissue for laboratory analysis, which is the only way to confirm or rule out a diagnosis of amelanotic melanoma.