Blue nevus

A blue nevus (Latin: naevus coeruleus) is a benign melanocytic tumor of the skin, originating from melanocytes located deep in the dermis. The characteristic blue-gray or navy color of the lesion is due to the so-called Tyndall effect – an optical phenomenon involving the scattering of light in the deeper layers of the skin. The lesion typically appears as a well-defined papule or patch with a diameter ranging from several millimeters to about 1 cm. It usually occurs as a solitary lesion, can be present from childhood, or may appear in early adulthood. In most cases, a blue nevus is benign and stable; however, like any pigmented lesion, it requires proper dermatological evaluation and periodic follow-up.

Blue nevus – what is it

A blue nevus is part of the group of benign dermal melanocytic nevi. Unlike typical pigmented nevi (located in the epidermis or at the dermo-epidermal junction), the melanocytes in a blue nevus are located deeper—in the dermis. This location is responsible for its bluish coloration.

There are two main clinico-histological types:

Common blue nevus

most common,
small (2–10 mm),
smooth, well-defined,
color ranges from blue-gray to navy,
stable over the years.

Cellular blue nevus

larger (often >1 cm),
may be more elevated,
more commonly located in the area of the buttocks, sacrum, scalp,
requires special differential monitoring.

Most common locations:

dorsal surfaces of the hands and feet,
face,
buttocks and lumbar area,
scalp.

In dermoscopic examination, a blue nevus usually presents a homogeneous, steel-blue or blue-gray structure without a pigment network. The absence of atypical structures indicates a benign nature, but any lesion with atypical growth dynamics requires further diagnostics.

Blue nevus – is it dangerous

In the vast majority of cases, a blue nevus is a benign lesion and does not pose an oncological threat. Transformation into melanoma developing on the basis of a blue nevus is a very rare phenomenon.

Factors requiring increased vigilance:

rapid growth of the lesion,
change in shape or color,
appearance of irregular borders,
ulceration or bleeding,
pain symptoms.

Particular attention is required for:

cellular blue nevus,
lesions with a diameter exceeding 1–2 cm,
lesions with atypical location or asymmetry.

In differential diagnosis, the following should be considered:

melanoma (especially the nodular form),
metastasis of melanoma to the skin,
hemangiomas,
dark-colored dermatofibroma.

In case of doubt, the following are performed:

dermoscopy,
videodermoscopy with photographic documentation,
in justified cases - surgical excision with histopathological examination.

It is crucial to distinguish between a stable lesion that has existed for years and a newly developed, dynamically changing pigmented structure.

Blue nevus – treatment

The treatment of a blue nevus involves its surgical excision in its entirety, if there are medical or aesthetic indications. The procedure:

is performed under local anesthesia,
involves removing the lesion with a small margin of healthy skin,
ends with stitching the wound and sending the specimen for histopathological examination.

In the case of small lesions, the prognosis is very good, and recurrences after complete excision are rare.

Post-procedure management includes:

monitoring wound healing,
removal of stitches after 7–14 days (depending on the location),
evaluation of the histopathological examination result.

In the context of dermatological procedures performed in clinical settings, it is also possible to surgically remove benign skin lesions, such as:

pigmented nevi,
fibromas,
warts,
sebaceous cysts.

Qualification for the procedure should always be based on reliable diagnostics and oncological principles. In the case of pigmented lesions, the primary goal is diagnostic safety, not merely an aesthetic result.