Blue Nevus (ICD-10: D22) ⚠️

Blue Nevus

Blue Nevus (also known as the blue nevus of Jadassohn–Tièche, blue neuronevus, or dermal melanocytoma) is a benign skin growth that is primarily characterized by its distinct blue to dark blue coloration. This type of nevus typically appears during puberty, although it can manifest at any age, even at birth. Multiple blue nevi in one individual are rare. Statistically, blue nevi tend to occur more frequently in women compared to men.

Predisposing Factors

The exact cause of blue nevi remains unclear. However, several factors have been identified that may predispose individuals to develop these neoplasms. These factors may influence the likelihood of their appearance or growth:

• Genetic Factors: The development of blue nevi may be linked to an individual’s genetic background. In some cases, family history may play a role in their appearance.
• What is not established: Ultraviolet exposure, hormonal changes, trauma and viral infection are sometimes listed as causes of blue nevi. None of them is established as such. A blue nevus is a melanocytic nevus whose melanocytes sit deep in the dermis, and that depth — not any external trigger — is what gives the lesion its blue colour.

Diagnostics

The diagnosis of blue nevi typically involves a clinical examination, which includes a thorough visual inspection of the lesion as well as dermatoscopy. A typical, longstanding, homogeneously blue lesion can be diagnosed clinically and simply observed; it does not need to be biopsied. Biopsy or excision is appropriate for a lesion that is changing, one that has newly appeared in an adult, one that is atypical on dermatoscopy, or one where the diagnosis is uncertain.

Symptoms

Visually, a blue nevus appears as a small spot or a slightly elevated nodule on the skin. It is typically symmetrical, with shapes ranging from oval or round to spindle-like. The surface texture of the nevus is usually similar to that of the surrounding skin, which may be smooth or even glossy, especially in smaller nevi. In larger nevi, over 10 mm in diameter, the surface may appear slightly more textured or tuberous.

The edges of the blue nevus are generally blurred or ill-defined, although they are usually smooth. In some cases, large blue nevi may have uneven or jagged edges, which could be an indication of potential malignancy. The color of the nevus ranges from blue to dark blue, with shades of gray-blue or blue-brown occasionally visible, reflecting the depth at which the pigment is deposited in the dermis. The intensity of the color tends to fade from the center towards the periphery, and in larger nevi, color heterogeneity or spotting may be present, resulting in a polychromatic appearance.

Hair is typically absent in blue nevi, although in some cases, coarse, dark hair may grow around the edges of larger nevi, particularly in congenital forms.

Blue nevi generally do not exceed 10 mm in size, and their growth is typically slow. Nevi larger than 1 cm are quite rare and are referred to as “blue cell nevi.” On palpation, these nevi feel similar to normal skin but may be slightly firmer, especially when they protrude above the skin’s surface. There are no subjective symptoms or sensations associated with these nevi.

Blue nevi most commonly occur on the dorsal surfaces of the hands and feet, the scalp, and the buttocks.

Dermatoscopic Description

The hallmark of a blue nevus on dermatoscopy is a homogeneous, structureless blue or steel-blue pigmentation — blue colour with nothing inside it:

• Homogeneous, Structureless Blue Pigmentation: An even blue or steel-blue colour without internal structures. This is attributed to melanocytes lying in both the papillary (grey) and reticular (blue) layers of the dermis.
• Symmetry: The nevus tends to maintain a symmetrical appearance.
• Undefined Boundaries: The edges are usually not sharply defined but remain relatively smooth.
• Gradual Color Transition: The colour intensity diminishes progressively from the centre towards the edges.

What should raise concern is the opposite of that picture. A pigment network, dots, clods, streaks, visible vessels, or more than one colour within the lesion are not features of an ordinary blue nevus and point towards another diagnosis — melanoma in particular.

Differential Diagnosis

Blue nevi need to be distinguished from several other pigmented neoplasms, including:

• Post-inflammatory hyperpigmentation
• Congenital dermal melanocytosis
• Common pigmented nevi (simple or papillomatous)
• Hemangiomas
• Spitz nevi
• Dysplastic nevi
• Melanoma

A blue lesion should never be called a blue nevus on the strength of its colour alone. For a lesion that is new or changing, the list that matters is this one: nodular melanoma, a melanoma metastasis in the skin, a traumatic tattoo, and venous or other vascular lesions.

Risks

Common blue nevi are benign and usually remain stable throughout life. Malignant transformation is a rare concern and is associated particularly with cellular blue nevi rather than with ordinary ones. It should not be presented as something blue nevi generally do.

What does warrant attention is change: a lesion that alters in appearance, grows, becomes nodular, or develops new sensations such as itching or pain.

Multiple or large congenital blue nevi may also be associated with certain genetic conditions or syndromes, making it essential for these individuals to receive thorough and ongoing medical evaluation.

Tactics

A lesion you have not had looked at is a different matter from one a clinician has already identified. Monitoring follows assessment, not the other way round: a blue lesion that has not been examined should be shown to a dermatologist. Colour alone does not make a lesion a blue nevus, and nodular melanoma and cutaneous melanoma metastases can both appear blue.

Once a lesion has been assessed as a typical blue nevus and is stable, watching it between reviews is reasonable. Go back sooner if it enlarges, becomes nodular, develops structures or colours within the blue, bleeds, or becomes painful.

A healthcare provider will assess whether continuous monitoring is required or if the nevus should be surgically removed. Nevi that are subjected to repeated physical trauma from clothing, jewelry, or occupational activities should be considered for removal.

Photographic documentation of the nevus can provide valuable records, allowing for the detection of even minor changes over time. For individuals with multiple blue nevi, it is highly recommended to create a map of their skin neoplasms, which will simplify future observations and the identification of any new or altered formations.

How often someone with blue nevi should be examined depends on the lesions themselves and on their overall melanoma risk, rather than on the time of year. Regular mapping of skin neoplasms can aid in tracking any developments or changes in existing lesions.

Treatment

A typical, stable blue nevus does not have to be removed. Where excision is indicated — for a changing, atypical or diagnostically uncertain lesion, or one newly appearing in an adult — it is done with a classic, electric or radio scalpel, and the tissue is examined histologically.

Destructive treatments such as laser removal or cryotherapy are not advised for blue nevi due to potential risks and complications.

Prevention

The prevention of nevi formation and their potential for malignant transformation involves careful and considerate skin care:

• Limiting exposure to ultraviolet radiation, including avoiding tanning beds and excessive sun exposure.
• Using sunscreen and protective clothing during periods of peak sunlight.
• Avoiding chronic skin trauma from clothing, jewelry, or other external factors.
• Adhering to safety protocols when handling skin-damaging agents.
• Maintaining good personal hygiene and staying vigilant for any changes in skin health.

It is crucial to have regular exams of blue nevi, seek timely consultation with a specialist if any changes occur, and remove potentially harmful neoplasms as soon as possible to maintain skin health and prevent complications.