Blue naevus

Blue naevus
Synonyms	Blue nevus
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A blue naevus (or blue nevus) is a type of melanocytic nevus that is characterized by its distinctive blue color. This coloration is due to the Tyndall effect, where the melanin is located deeper in the dermis than in common moles.

Classification

Blue naevi can be classified into several types, including:

• Common blue naevus: Typically small, round, and blue to blue-black in color.
• Cellular blue naevus: Larger and more nodular than the common type, often found on the buttocks or sacrococcygeal region.
• Combined blue naevus: Contains features of both a blue naevus and another type of nevus, such as a junctional nevus.

Pathophysiology

The blue color of the naevus is due to the presence of melanin deep within the dermis. The Tyndall effect causes the shorter wavelengths of light to be scattered, giving the lesion its blue appearance.

Diagnosis

Diagnosis of a blue naevus is typically made through clinical examination. Dermatoscopy can aid in the evaluation of the lesion. In some cases, a biopsy may be performed to rule out malignant melanoma.

Treatment

Most blue naevi are benign and do not require treatment. However, if there is any suspicion of malignancy, or if the lesion changes in appearance, surgical excision may be recommended.

Prognosis

The prognosis for a blue naevus is generally excellent, as these lesions are typically benign. However, regular monitoring is advised to detect any changes that might suggest malignancy.

See also

• Melanoma
• Nevus
• Dermatology

External links

• DermNet NZ: Blue Naevus