Compound nevus
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Compound nevus (Latin: naevus compositus) is one of the most common types of melanocytic nevi, that is, benign pigmented skin lesions arising from melanin-producing cells – melanocytes. It is characterized by the presence of nests of pigment cells both in the epidermis and in the upper layer of the dermis. For this reason it represents an intermediate form between a junctional nevus (located exclusively in the epidermis) and an intradermal nevus (located mainly in the dermis). Clinically, a compound nevus most often appears as a small, well-demarcated pigmented lesion ranging in color from light brown to dark brown, often slightly raised above the skin surface. In the majority of cases a compound nevus is benign and does not pose a threat to health, however – like other melanocytic nevi – it requires periodic dermatological surveillance.
Compound nevus – types
Although the term "compound nevus" refers primarily to a specific histopathological type of melanocytic nevus, in clinical practice several variants can be distinguished, differing in appearance, location and growth dynamics. The basis of classification is both the clinical presentation and the structure of the lesion on dermatoscopic and histopathological examination.
The most common variants include:
1. Classic compound nevus
- usually small (a few millimetres in diameter),
- slightly raised or dome-shaped,
- light brown or medium brown in colour,
- typically symmetric in shape with regular borders.
2. Papillomatous compound nevus
- has an uneven, papillomatous surface,
- may be more elevated above the skin surface,
- may resemble a small pigmented papule.
3. Hairy compound nevus
- hairs may grow within the lesion,
- this is a physiological phenomenon and does not indicate a neoplastic process.
Biologically, compound nevi arise as a result of proliferation of melanocytes, which form nests both in the basal layer of the epidermis and in the upper part of the dermis. Over the course of life these lesions may gradually evolve – with age melanocytic cells migrate deeper into the dermis, leading to the formation of dermal nevi.
Compound nevi most commonly appear on:
- the trunk,
- the limbs,
- the face.
Their number in a given person can vary and depends on genetic factors and exposure to ultraviolet radiation.
Compound nevus – what does it mean
In most cases a compound nevus is a benign melanocytic lesion that does not pose a threat to health. Its presence merely indicates a local accumulation of pigment cells in specific layers of the skin. In many people these types of nevi appear in childhood or during adolescence, when melanocyte activity is higher.
The formation of melanocytic nevi is associated with several factors:
- genetic factors,
- exposure to UV radiation,
- hormonal changes (e.g., during puberty or pregnancy),
- the individual tendency of the skin to form nevi.
Although a compound nevus is a benign lesion, its dermatoscopic monitoring is of great importance in dermatology. Dermatoscopic examination allows assessment of the lesion's structure and detection of any worrisome features that may suggest malignant transformation.
Symptoms requiring dermatological consultation include, above all:
- rapid enlargement of the nevus,
- change in color or the appearance of multiple pigment shades,
- irregular borders of the lesion,
- bleeding or ulceration,
- the onset of itching or pain.
In the differential diagnosis of melanocytic nevi particular attention is paid to the possibility of the development of cutaneous melanoma, a malignant tumor originating from melanocytes. Therefore, in the case of lesions with an atypical appearance the physician may recommend their removal and histopathological evaluation.
Compound nevus – removal
Removal of a compound nevus is not always necessary. In many cases regular dermatological check-ups and observation of the lesion in a dermatoscopic examination are sufficient. However, there are situations in which a doctor may recommend removal of the nevus.
The most common indications for the procedure include:
- suspected malignant lesion,
- rapid enlargement of the nevus,
- changes in the lesion's structure or color,
- chronic mechanical irritation (e.g., from clothing or jewelry),
- cosmetic reasons.
The most reliable treatment method is surgical excision of the lesion with a margin of healthy tissue. The procedure is performed under local anesthesia, and the removed tissue is always sent for histopathological examination. Microscopic analysis allows definitive confirmation of the lesion's nature and exclusion of cancerous cells.
In aesthetic dermatology and dermatosurgery, other methods are also used to remove selected skin lesions, including:
- laser removal of pigmented lesions,
- electrosurgery,
- dermatologic surgical procedures performed on an outpatient basis.
It is worth emphasizing, however, that in the case of melanocytic nevi of uncertain character surgical excision remains the preferred method, because it allows for full histopathological assessment. For this reason, physicians often do not recommend laser removal of pigmented lesions that may require microscopic evaluation, since this method does not permit a thorough histopathological examination of the removed tissue.
Regular monitoring of moles – especially in people with a large number of them – is one of the most important elements of skin melanoma prevention. Dermatologists recommend undergoing a dermatoscopic examination at least once a year, and more frequently for those in higher-risk groups.
