Summary about Disease
A blue nevus is a type of melanocytic nevus (a mole) characterized by its blue or blue-black color. This coloration arises from the deep location of melanin pigment within the skin. While usually benign (non-cancerous), a blue nevus can sometimes resemble a melanoma, which necessitates careful diagnosis and monitoring. Common types include common blue nevus, cellular blue nevus, and atypical blue nevus.
Symptoms
A small, usually round or oval, blue or blue-black colored mole.
Typically smooth surface.
Usually solitary (only one).
Most commonly found on the dorsal hands and feet, buttocks, and scalp, but can occur anywhere on the body.
Generally asymptomatic (doesn't cause pain, itching, or other sensations).
Size typically from a few millimeters to 1-2 cm.
Causes
Blue nevi are caused by the presence of melanocytes (pigment-producing cells) deep within the dermis (the deeper layer of the skin). These melanocytes produce melanin, the pigment responsible for skin color. The Tyndall effect, a physical phenomenon, causes the blue appearance. In the Tyndall effect, shorter wavelengths of light (blue) are scattered when light passes through a colloid solution (in this case, the skin and dermis), giving the lesion a blue hue. The exact reason why melanocytes migrate and proliferate deep within the dermis in blue nevi is not fully understood, but genetic factors and/or environmental triggers are suspected.
Medicine Used
There are no specific medications to treat blue nevi directly. Since blue nevi are typically benign, treatment is usually not required. However, if a blue nevus is atypical, growing rapidly, changing in color or shape, or is clinically suspicious, it may be surgically excised (removed). Topical treatments are ineffective because the pigment is located too deep in the skin.
Is Communicable
No, a blue nevus is not communicable. It is not caused by an infection or any contagious agent and cannot be spread from person to person.
Precautions
Regular Skin Exams: Conduct self-skin exams regularly to monitor for any changes in existing moles or the appearance of new ones.
Sun Protection: Protect your skin from excessive sun exposure by using sunscreen with a high SPF, wearing protective clothing, and seeking shade during peak sun hours. While sun exposure doesn't directly cause blue nevi, it is important for overall skin health and can reduce the risk of other skin cancers.
Professional Skin Exams: See a dermatologist annually, or more frequently if you have a personal or family history of skin cancer, for a professional skin exam.
Monitor for Changes: Any changes in the size, shape, color, or texture of a mole, especially a blue nevus, should be evaluated by a dermatologist.
How long does an outbreak last?
Blue nevi are not an "outbreak." They are persistent lesions. They typically do not resolve on their own. They are present continuously unless surgically removed.
How is it diagnosed?
Visual Examination: A dermatologist will visually examine the lesion.
Dermoscopy: A dermatoscope, a handheld magnifying device with a light source, is used to examine the mole's structures in more detail.
Biopsy: If the dermatologist suspects malignancy or if the diagnosis is uncertain, a biopsy may be performed. This involves removing a small sample of the lesion for microscopic examination by a pathologist. There are various biopsy methods, including shave biopsy, punch biopsy, and excisional biopsy.
Histopathology: Microscopic examination of the biopsy specimen will confirm the diagnosis and rule out melanoma or other skin cancers.
Timeline of Symptoms
The appearance of a blue nevus is generally sudden. The typical timeline is:
Appearance: A small blue or blue-black spot appears on the skin.
Growth (if any): The lesion may slowly enlarge over time, but usually remains small.
Stability: Typically, the size, shape, and color remain stable.
Changes (if atypical): Rarely, the lesion may rapidly change in size, shape, or color, warranting immediate medical attention.
Important Considerations
Differentiation from Melanoma: The primary concern with blue nevi is distinguishing them from melanoma, a potentially life-threatening skin cancer. Atypical blue nevi, in particular, can be difficult to differentiate from melanoma, so careful evaluation is critical.
Atypical Blue Nevi: These have features that are concerning and may require complete excision.
Cellular Blue Nevi: Larger and may be confused with melanoma. Complete excision is recommended.
Congenital vs. Acquired: Blue nevi can be present at birth (congenital) or develop later in life (acquired).
Location: Certain locations, such as the scalp or buttocks, may have a slightly higher risk of atypical features.
Patient Anxiety: The blue color can be concerning for patients, so a thorough explanation of the diagnosis and prognosis is important.