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Basics ⬇

Clinical Variant ⬆ ⬇

Sporadic Atypical Nevi !!navigator!!

  • A patient with an isolated atypical nevus and no family history of multiple atypical nevi or melanoma probably carries little risk of developing melanoma and should not necessarily be identified as prone to melanoma.

Multiple Atypical Nevi !!navigator!!

  • The exact risk of an individual nevus developing into a melanoma is uncertain.

  • In certain situations atypical nevi are considered possible precursors to, as well as potential markers for, the development of melanoma that may occur de novo without evolving from a precursor dysplastic nevus.

Familial Atypical Mole Syndrome !!navigator!!

  • Those persons who meet the following criteria are considered to have an extremely high potential for developing malignant melanoma:

    1. Patients with a first-degree (e.g., parent, sibling, or child) or second-degree (e.g., grandparent, grandchild, aunt, uncle) relative who has a history of malignant melanoma have heightened risk.

    2. Many nevi—often more than 50—are present, and some of them are atypical moles.

    3. Having moles that show certain dysplastic features microscopically.

Diagnosis-icon.jpg Differential Diagnosis

Other Melanocytic Nevi (see earlier Discussion)
Malignant Melanoma

  • Brownish to blue-black pigmentation are often seen in more darkly pigmented persons.

Seborrheic Keratosis (see below)

  • May be indistinguishable from a nevus or a pigmented basal cell carcinoma.

  • Dermoscopic evaluation of the lesion will help confirm the diagnosis.

Management-icon.jpg Management

  • The method chosen for removing suspected atypical nevi depends on the purpose of treatment.

  • If melanoma is suspected, complete excision should be performed.

  • If melanoma is not suspected, the lesion can be removed and prepared for biopsy with a shave or punch biopsy technique.

Prevention

  • Patients with many atypical nevi should avoid excessive sun exposure and should routinely use a broad spectrum sunscreen with a sun-protective factor of greater than 50.

  • Patients who meet the criteria for familial atypical mole syndrome should examine their own skin every 2 to 3 months, in addition to having a full body examination and regular screening visits performed by a dermatologist.

  • High-risk patients and their families should be taught self-examination to detect changes in existing moles and should be given printed material with photographs to help them recognize the features of malignant melanoma.

Helpful-Hint-icon.jpg Helpful Hint

  • Despite the fact that patients with many dysplastic nevi are at a higher risk of developing a melanoma, the notion of removing all of their dysplastic nevi to reduce their risk of melanoma is generally believed to be ill advised. To consider all of these nevi to be precursors of melanomas creates undo anxiety for patients but does not appear to decrease their potential for developing melanomas.

Point-Remember-icon.jpg Points to Remember

  • Once a diagnosis of multiple atypical nevi is established, other family members should be examined.

  • Melanoma risk is greater in those persons who have one relative with melanoma than in those with no affected relative. The lifetime risk of melanoma may approach 100% in persons with atypical nevi who are from melanoma-prone families (i.e., individuals having two or more first-degree relatives with melanoma).

  • Patients with the familial atypical mole syndrome (also known as the dysplastic nevus syndrome) should be monitored vigilantly.

SEE PATIENT HANDOUT “Atypical Nevus (Mole)” IN THE COMPANION eBOOK EDITION.

Outline

Diagnosis ⬆ ⬇

  • The diagnosis is based on clinical appearance or, if necessary, a histopathologic evaluation after removal.

Diagnosis-icon.jpg Differential Diagnosis of Dermal Nevus and Compound Nevus

Dermal nevi and compound nevi often are clinically indistinguishable from one another as well as the following:

Skin Tags (Acrochordons [see later in this chapter])

  • 1- to 10-mm fleshy papules.

  • Skin-toned, tan, or darker than the patient's skin.

  • Most often arise on the neck, axillae, inframammary area, inguinal crease, and the eyelids.

Seborrheic Keratosis (see later in this chapter)

  • Adults >50 years old.

  • Warty, “stuck-on” appearance that ranges from tan to dark brown to black.

  • Scaly, flat, or almost flat or small pigmented papules

  • Most often are located on the back, chest, and face, the frontal hairline and scalp. They are also frequently found on the arms, legs, and abdomen.

Basal Cell Carcinoma (see Discussion in Chapter 31: Premalignant and Malignant Cutaneous Neoplasms)

  • Age generally >40 years old.

  • Sun-exposed areas.

  • Pearly papules with rolled (raised) border and telangiectases with or without ulceration.

Angiofibroma (Fibrous Papule of the Nose [see later in this chapter])

  • Most are noted on the nose; less commonly, on the cheeks and chin.

  • May be difficult to distinguish from compound or dermal nevus or basal cell carcinoma.

  • Generally dome-shaped, flesh-colored, pale, or pink firm papules with a shiny appearance.

Neurofibroma/Neuroid Nevus

  • Very soft, flesh colored

Nodular Melanoma (see Discussion in Chapter 31: Premalignant and Malignant Cutaneous Neoplasms)

Helpful-Hint-icon.jpg Helpful Hint

  • With few exceptions such as blue nevi (discussed below), lesions that arise after the age of 30 are unlikely to be melanocytic nevi.

Other Information ⬆

Junctional Melanocytic Nevus !!navigator!!

  • These small, macular (flat), frecklelike lesions are uniform in color. Individual lesions may be brown to dark brown to black (Fig. 30.1).

  • Histologic examination reveals melanocytic nevus cells located at the dermoepidermal junction.

  • Whether acquired or congenital, junctional MN are most prevalent on the face, arms, legs, trunk, genitalia, palms, and soles (Fig. 30.2).

Compound Melanocytic Nevus !!navigator!!

  • Compound MN are elevated dome-shaped papules or nodules.

  • Uniformly brown to dark brown, or black; they may contain hairs.

  • Seen most often on the face (Figs. 30.3 and 30.4), arms, legs, and trunk.

  • Their histologic findings combine features of junctional and dermal nevi.

Diagnosis-icon.jpg Differential Diagnosis

In Children
Freckles (Ephelides)

  • Small, tan macules appear on the sun-exposed skin of fair-skinned people.

  • They darken after sun exposure and lighten when they are no longer exposed to the sun.

In Adults
Dysplastic Nevus ([Atypical Nevus] see Discussion below)

  • Most often arise on the trunk, legs, and arms and spares the face.

  • Usually larger than common nevi.

  • Borders are generally irregular, notched, and ill-defined.

  • The centers may be raised (sunny-side-up egg) appearance.

  • Coloration (tan, brown, black, pink, or red) is irregular.

In Adults and Elderly
Lentigo (Plural: Lentigines) or “Liver Spot” (see below)

  • Sun-exposed areas (face, flexor forearms).

Lentigo Maligna and Melanoma (see Discussion in Chapter 31: Premalignant and Malignant Cutaneous Neoplasms)

Dermal Melanocytic Nevus !!navigator!!

  • Dermal MN may be elevated and dome-shaped, wartlike, or pedunculated.

  • Most often skin-colored, but they may also be tan or brown, or they may be dappled with pigmentation.

  • Lesions tend to lose pigmentation with age and become skin-colored (Fig. 30.5).

  • Most often noted on the face and neck.

  • Microscopy reveals dermal MN cells located in the dermis.

Clinical Manifestations of Dermal and Compound Nevi !!navigator!!

  • Both are asymptomatic unless irritated or inflamed.

  • Very rarely do they transform into malignant melanoma.

Blue Nevus !!navigator!!

  • Blue nevi are a benign variant of dermal melanocytic nevi (MN) that are heavily pigmented.

  • They occur as blue-gray or blue-black macules, papules, or nodules (Fig. 30.6). They are rarely malignant.

  • The dark brown pigment that creates a bluish color to these lesions is caused by the Tyndall phenomenon.

  • Blue nevi usually begin to appear in adolescence, early adulthood, or middle age.

Halo Nevus !!navigator!!

  • Halo nevi are MN that are encircled by a white halo of depigmentation. The halo represents a regression of a pre-existing nevus initiated by a lymphocytic infiltrate. Frequently, the entire nevus disappears, and the area regains normal pigmentation.

  • Most often, halo nevi are initially seen on preadolescents; usually appearing on the trunk (Fig. 30.7).

  • If a halo nevus is seen on an adult, two very rare possibilities should be considered: The lesion may be a melanoma or a melanoma may be present elsewhere on the body. Biopsy and removal are indicated in this situation.

Spitz Nevus !!navigator!!

  • These nevi are a distinctive variant of MN. In the past, they were referred to as “juvenile melanomas,” but now they are mostly recognized as benign lesions in children.

  • In children, the lesions may appear as pink papules or a heavily pigmented lesion that is jet black in color (see Chapter 1: Birthmarks).

  • A heavily pigmented, small, spindle-cell variant of Spitz nevus may be seen on the legs of women.

  • Treatment of Spitz nevi is controversial. Most pediatric dermatologists agree that most Spitz nevi are benign lesions; however, in adults, it is prudent to completely excise these lesions to minimize the risk of recurrence and possible confusion with a malignant lesion.

Congenital Melanocytic Nevus (see Chapter 1: Birthmarks) !!navigator!!

  • Often generating great concern in both patents and pediatricians, congenital melanocytic nevi (CMN) are MN that are present at birth or arise during the first year of life.

  • By definition, CMN are present at birth or soon thereafter, although some small CMN are the so-called “tardive,” and may appear as late as up to 2 years of age.

  • CMN occur in about 1% of children.

Management-icon.jpg Management of Melanocytic Nevi

  • All MN should be carefully examined and biopsy should be considered, particularly if there is any suggestion of atypia clinically.

  • However, for most MN, biopsy is not indicated. Persons with numerous MN, particularly atypical nevi (see later discussion), are at greater risk for developing malignant melanoma.

Indications for Removal

  • Atypical appearance.

  • Cosmetic reasons.

  • Repeated irritation by clothing, such as a bra strap

  • Persistent discomfort (e.g., a lesion that itches, hurts, or bleeds).

Methods of Removal

Lesions can be removed by shave excision (which is often followed by electrodesiccation) or by elliptic excision (see Chapter 35: Diagnostic and Therapeutic Techniques).

  • Shave (tangential) excision: This method is fast and economical, and it generally provides satisfactory cosmetic results. Its disadvantage is that it often results in only partial removal of lesions, which infrequently necessitates a second excisional procedure.

  • Elliptical excision: This technique is performed with the intent of removing lesions completely; thus surgical margins can be identified. However, an elliptical excision takes longer to do than a shave biopsy. It also requires suturing and suture removal, and it results in linear scars that may not be as cosmetically pleasing as scars that result from shave excisions.

Point-Remember-icon.jpg Points to Remember

  • Any pigmented lesion that changes rapidly in size or color or that has an atypical appearance should be removed for biopsy.

  • A primary care physician should have a low threshold for referral to a dermatologist if there is any concern regarding the diagnosis and management of a pigmented lesion.

  • All MN that are removed should be submitted for microscopic evaluation.

  • Large CMN have a low but real risk of malignant transformation and the development of melanoma (see Chapter 1: Birthmarks).

Atypical Melanocytic Nevus (Dysplastic Nevus, Clark Nevus) !!navigator!!

Basics

  • The atypical nevus, which is also called dysplastic nevus, an atypical mole, or Clark nevus, is a controversial and confusing lesion. Nevi that are clinically atypical are not always dysplastic under the microscope. Even among dermatopathologists, there is no consensus regarding the histopathologic criteria for a dysplastic nevus.

  • Some individuals have only a few atypical nevi, and their risk of melanoma may not be much higher than those individuals without such nevi.

  • This much is agreed: When a patient has numerous atypical nevi and there is a positive family history of melanoma, the potential for melanoma in that patient, as well as in his or her family is extremely high. Such atypical nevi may be inherited as an autosomal dominant trait (see discussion below of familial atypical mole syndrome).

  • Atypical nevi are rarely seen in black, Asian, or Middle Eastern populations.

Clinical Manifestations

Atypical nevi have some or all of the following features:

  • Atypical nevi are most often found on the trunk (Fig. 30.8), legs, and arms; generally, the face is spared.

  • They are usually larger than common moles and frequently measure 5 to 15 mm in diameter.

  • Their borders are usually irregular, notched, and ill-defined.

  • They have a macular appearance, but the centers may be raised (for this reason, they are sometimes called “sunny-side-up egg lesions”) (Fig. 30.9).

  • Their coloration (tan, brown, black, pink, or red) is irregular.

  • The exact risk of an individual atypical nevus developing into a melanoma is uncertain.

  • Unlike dermal and compound nevi, these lesions often continue to appear into adulthood.

  • Differentiating them clinically from melanoma is often difficult.

Outline