Skin moles

Skin moles appear during the first few years of life. Most people have 20-30; some have many more. The common skin mole should be uniformly pigmented, with a regular margin. A halo of pale skin around a skin mole may be seen in adolescence. Occasionally congenital skin moles are large (greater than 1 cm), multiple or confluent (bathing trunk pattern). These lesions carry a risk of malignant transformation. Skin Moles deeper in the dermis appear blue in color. Skin Moles tend to regress in old age. If skin moles change in size, become irregular in shape or pigmentation, itch or bleed they should be regarded as unstable and potentially malignant. Sunburn can irritate and activate skin moles. During pregnancy, skin moles tend to increase in size and darken. Malignant melanomas can arise de novo or from pre-existing skin moles. The incidence of this malignant tumor is increasing, especially in fair-skinned people with high sun-exposure.

Atypical Skin Moles Features

Atypical Skin Moles do not follow an evolutionary pattern of either persistence with stability or differentiation in the direction of ultimate regression, as seen in Common Acquired Melanocytic Skin Moles. Rather, Atypical Skin Moles demonstrate a persistent and disordered growth, evident both clinically and microscopically. The clinical recognition of Atypical Skin Moles focuses on several characteristics that help distinguish them from Common Acquired Melanocytic Skin Moles: shape, border, color, diameter, and surface features. Many of these features may also be seen in melanoma, although often to a greater degree.
1 Shape: The shape may be round or oval, like the common acquired Skin Mole, although asymmetric notching and/or outgrowth of pseudopodia are usually observed in lesions over 3 to 4 mm in diameter.
2 Border: The boundary may be irregular with slightly indiscrete to frankly hazy or fuzzy areas, with traces of pink or brownish pigment spilling into surrounding normal skin.
3 Color: The coloration of Atypical Skin Moles is often variegated, with irregular speckling with tan/brown colors and sometimes including foci of tan/brown/dark brown hues or black pigment. redness may be seen as a component of Atypical Skin Moles but is not normally seen in Common Acquired Melanocytic Skin Moles. This is manifest as a pink background color, the intensity of which may vary from trace to slight to moderate. Sometimes only a focal area of pink or a subtle pink hue at the periphery may be seen. The redness does not blanch readily; the degree of redness varies considerably from lesion to lesion and from patient to patient.
4 Diameter: Atypical Skin Moles are most easily recognized when larger than 5mmin diameter. The Clark group’s initial description of Atypical Skin Moles in BK mole syndrome patients had emphasized that they were frequently 5 to 10 mm or larger, and that size was an important clue in identifying Atypical Skin Moles. Large size, however, is not a prerequisite for the diagnosis of Atypical Skin Moles.
5 Surface features: The surface features within any given Atypical Skin Mole may include macular and papular components. A minimal elevation to tangential lighting is noted in most of them. The skin surface markings may be suggestive of early lichen simplex chronicus, showing subtle elevation and coarsening. Scale is only infrequently noted. Erosion is not seen in the non traumatized Atypical Skin Mole.
The clinical presentation of patients with Atypical Skin Moles seems as varied as the morphology of individual Atypical Skin Moles. The classical type D2 phenotype may be first evident with numerous distinctly large, irregular, variegate Skin Moles, mostly concentrated on the trunk and less numerous on the head, neck, and lower extremities. More commonly, however, Atypical Skin Moles are not strikingly large. Fromseveral to a dozen Atypical Skin Molesmay bemixed among several to several dozen Common Acquired Melanocytic Skin Moles. In patients with a solitary Atypical Skin Mole, it may be located anywhere.

Atypical Skin Moles

The atypical skin mole is a special kind of skin moles, with clinical and histologic features suggestive of an intermediate form between the common acquired skin mole and melanoma. atypical skin moles are important markers for both familial and nonfamilial melanoma. As many as 50% of patients with “sporadic” melanoma have been observed to have atypical skin moles.
The incidence of atypical skin moles in the general population has been estimated to be 1.8% to 10% and possibly as high as 19%. The presence of atypical skin moles has been established as an independent risk factor for melanoma, along with several other cutaneous traits, including red or blonde hair, solar lentigines, skin type 1 or 2, and increased numbers of common acquired skin moles. A clinical study has found the adjusted relative risk of melanoma to be 2 for a single atypical skin mole and 12 for 10 or more atypical skin moles. Another found a relative risk of 1.6 when one to four atypical skin moles were counted and 6.1 for five or more atypical skin moles. The risk ofmelanoma attributable to atypical skin moles may
be further exacerbated by the coexistence of other melanoma risk factors, such as skin type 1 or 2. The increased risk for melanoma is particularly true in the setting of the atypical skin mole syndrome (Dysplastic Nevus Syndrome). Dysplastic Nevus Syndrome encompasses individuals with multiple atypical skin moles arising sporadically or in a setting of a family history of atypical skin moles or melanoma. Dysplastic Nevus Syndrome has been divided into a number of forms. Type A is sporadic dysplastic skin mole without melanoma; type B is familial atypical skin mole without melanoma; type C is sporadic atypical skin mole with a personal history of melanoma; type D-l is familial atypical skin mole with one family member with melanoma; and type D-2 is familial atypical skin mole with two or more family members with melanoma. Meticulous screening of family members may demonstrate that presumptive cases of sporadic Dysplastic Nevus Syndrome are actually familial.
All patients with Dysplastic Nevus Syndrome have an increased risk for developing melanoma, although the magnitude of the risk varies among the Dysplastic Nevus Syndrome types. The relative risk of melanoma is least in patients with Dysplastic Nevus Syndrome types A and B, and has been estimated to be 7 with a cumulative lifetime risk of 6%. The relative risk of melanoma in type D-2 patients may be as high as 1000 or greater compared with the general population. Individuals with Dysplastic Nevus Syndrome also appear to be at an increased risk for multiple primary cutaneous melanomas.One study found a 35.5% cumulative 10-year risk of developing a secondmelanoma in those with Dysplastic Nevus Syndrome and a history of melanoma as compared with a 17% 10-year risk of developing a second melanoma in those with a history of melanoma butwithoutDysplastic Nevus Syndrome . Patients with Dysplastic Nevus Syndrome may also be at increased risk of conjunctival and intraocular melanoma. The recognition of Dysplastic Nevus Syndrome may allow early detection of melanoma and identi?cation of those at risk and provide the opportunity for the initiation of preventive measures.
A great deal of discussion has centered on the validity of the atypical skin mole as a distinct entity and its potential for progression to melanoma. Much disagreement over its nature stems from a lack of uniform clinical and histologic criteria to define it. In fact, even the term atypical skin mole has contributed to the controversy. Strictly speaking, the term atypical is a histologic one. The purist may object to the clinical description of a melanocytic skin mole as “atypical-looking". atypical skin moles generally demonstrate both clinical and histologic evidence of distorted and disordered architecture. A
statement by the National Institutes of Health (NIH) Consensus Conference in 1992 sought to eliminate the variability in nomenclature and recommended that the term dysplastic nevus be replaced with atypical mole and the histologic diagnosis be termed nevi with architectural disorder along with a description of the degree of melanocytic atypia. A 2004 survey revealed that the term dysplastic nevus remains commonplace.

Skin moles in relation to melanoma

Skin moles, which are benign melanocytic lesions, may have occasional cosmetic significance but, for the most part, they are important only in relation to malignant melanoma. skin moles are the most important simulants of malignant melanoma, both clinically and histologically, and can usually be reliably distinguished from malignant melanomas using specific criteria. Some nevi are characterized by greater degrees of atypia and may be more difficult to diagnose. Atypical skin moles are among the most important simulants of malignant melanoma. Skin moles may also be important as potential precursors of malignant melanoma; however, most skin moles are stable and will not progress to malignancy. Skin moles are vastly more common than malignant melanomas and the rate of progression of individual nevi is very low. Therefore, skin moles are not as a rule managed by wholesale excision to prevent malignant melanoma. Skin moles are also important as risk markers, identifying individuals at greater risk of developing malignant melanoma in the future. Atypical skin moles and, to a lesser extent, common acquired and congenital skin moles are among the most important malignant melanoma risk markers. Skin moles of special sites have been identified as skin moles that may show atypical features suggestive of an atypical skin mole or of a malignant melanoma. However, they are not risk markers and they are not malignancies. skin moles of genital skin, acral skin, and flexural skin are among the most important 'skin moles of special sites'. It is important, in considering the differential diagnosis of a nevus in a special site, to avoid overcalling such a nevus as a malignant melanoma or an atypical skin mole because this could lead to excessive treatment. Conversely, it is important to avoid undercalling a nevus that is an atypical skin mole or a malignant melanoma as a skin mole of special sites, because in this circumstance a patient could lose the opportunity either for surveillance to recognize a developing malignant melanoma at an early, curable stage, or for definitive treatment of an established malignancy.

What are Skin Moles

Skin Moles are benign neoplasms of melanocytes. Junctional Skin Moles are localized collections of neval melanocytes found in the epidermis and superficial dermis, they are flat and pigmented. Compound Skin Moles are localized collections in the epidermis and superficial and deep dermis, these Skin Moles are pigmented and raised. Intradermal Skin Moles are localized collections in the deep dermis with no involvement of the epidermis or junctional dermis, such Skin Moles are flat and flesh-colored. Most Skin Moles are absent at birth. They tend to first appear and increase in number during childhood, reaching their maximum in early adulthood. Skin Moles counts have been shown to increase at an earlier age in Caucasians who live closer to the equator, where sun exposure and intensity is greatest.
Large numbers of Skin Moles, both common acquired Skin Moles and atypical Skin Moles, are markers of individuals who are susceptible to developing melanoma. Atypical Skin Moles are large (+6 mm) compound Skin Moles often with a surrounding macular erythematous component, irregular in color or shape, but nevertheless benign. These lesions may or may not show histological evidence of dysplasia, therefore the old term ‘dysplastic Skin Moles’, which leads to much confusion, is not recommended. Although the clinical differentiation of atypical Skin Moles from melanoma is difficult, it may be facilitated by regular surveillance and clinical photography. The presence of more than five atypical skin moles on a person has been shown to be a powerful and independent marker of melanoma susceptibility.
‘Congenital Skin Moles’ is a term applied both to compound Skin Moles present at birth and to acquired Skin Moles that are clinically and histologically similar to skin moles present at birth. One child in 100 is born with a congenital pigmented nevus, while 6 to 12 per cent of children and adults have a ‘congenital type nevus’. The risk of evolution of a small congenital nevus (-2 cm) into invasive melanoma is unknown, but is thought to be much less than 1 per cent. Prophylactic excision is not universally advocated, but rather considered on a case-by-case basis. Large congenital Skin Moles (20 cm) occur in 1 in 500 000 births and probably carry a 4 to 6 per cent risk of progression to melanoma over a lifetime. The melanoma usually develops after puberty and does not always occur in the nevus itself. Unfortunately, removal of large lesions is rarely easy and may involve numerous surgical procedures.
There may be a natural evolution of acquired Skin Moles from junctional to compound to intradermal Skin Moles. The malignant potential of individual lesions is low, therefore prophylactic excision of acquired Skin Moles to prevent transformation into melanoma is not advised. Most melanomas arise de novo in the absence of any clinical or histological evidence of a pre-existing nevus. Excision of Skin Moles is advocated where it is not possible to clinically exclude a diagnosis of melanoma. The lesion should be totally excised and submitted for histological assessment. Destructive therapy of Skin Moles without histological assessment is a recipe for disaster, for clinical diagnosis is not completely accurate and an opportunity to re-excise an incompletely or inadequately removed tumor may be missed. Patients who subsequently present with metastatic melanoma without an identified primary will rightly or wrongly point the finger at the physician who removed the ‘nevus’, and claim compensation. Therefore, complete removal and histological examination is advocated even when moles are removed for purely cosmetic reasons.

What are Atypical Nevi

Onset: begin to appear during early childhood. The characteristic features of atypical moles are present at the time of puberty. Unlike common acquired melanocytic nevi, which stop appearing after age 30, atypical nevi continue to appear well into adulthood.
Size: ranging from 6 mm-15 mm in diameter.
Border: irregularly outlined, indistinct, and fades imperceptibly into the surrounding skin.
Color: variegated with a haphazard mixture of pink, tan, brown, and black.
Surface: irregular, often with a central or eccentric papule surrounded by a prominent macular component.
Site: anywhere in the skin but occur most commonly on the trunk and upper extremities. Affected persons often have nevi in sun-protected areas, such as the scalp, groin, buttocks, the breasts in women, and the palms and soles.
Progression: increased risk of melanoma, most often the superficial spreading type.

What are Congenital Melanocytic Nevi

Incidence: About 1% of newborns have at least one melanocytic nevus.

Onset: Present at birth, or appearing by age 2.

Course: The vast majority of congenital melanocytic nevi are benign and follow a life-long course of maturation. They increase in size and become more heavily pigmented during puberty.

Size: Congenital melanocytic nevi vary greatly in size.

Appearance: Congenital melanocytic nevi are considered to be a type of birthmark, of which there are many variants. They are usually dark brown and raised, with an irregular verrucous surface. Most have increased coarse terminal hairs.

Symptoms: Depending on their location, large lesions may be disfiguring.

Diagnosis: Depending on their onset, course and appearance, most congenital nevi are diagnosed. Nevi which deviate from the urdinary pattern of maturation are suspicious and biopsy is warranted.

Histopathology: Congenital nevi are benign skin tumors composed of melanocyte-derived nevus cells, they are usually compound nevi with nested nevus cells at the junction and also in the dermis. Nevus cells may extend into fat and invest adnexal structures and blood vessels.

Progression: The risk of malignant transformation is increased in giant congenital melanocytic nevi with diameters greater than 20 cm with a lifetime risk of 5-8%. Melanoma developing in smaller congenital nevi may have an increased lifetime risk in those larger than 2 cm.

Treatment: Nevus cells in congenital nevi often extend into subcutaneous fat, therefore a malignant change may not be easily detected. For this reason, elective excision when feasible (usually around the time of puberty) is favored.
















Melanoma developing in a congenital nevus

What are Dermal Nevi

Onset: mainly after adolescence
Site: generally appear on the face
Origin: Nests and cords of nevus cells are found within the dermis; they may extend into the subcutaneous fat
Size: vary in size from a few millimeters to a centimeter
Shape: Dome-shaped lesions are the most common, The variety of shapes reflects the evolutionary process in which moles extend downward with age and nevus cells degenerate or become replaced by fat and fibrous tissue
Appearance: elevated, fleshy, and slightly or moderately pigmented papules, may appear as a soft, flabby, wrinkled sack
Surface: smooth, may be white or translucent, with telangiectatic vessels
Color: brown or black, but may become lighter or flesh-colored with time
Border: symmetric, white borders may appear, creating a halo nevus
Special features: Pigmentation may be arranged in flecks. Coarse, dark, terminal hairs may grow from the nevus. may be warty or polypoid. Pedunculated lesions with a narrow stalk are located on the trunk, neck, axilla, and groin
Complications: prone to trauma from clothing and other stimuli, often causing them to bleed
Progress: Degeneration into melanoma is rare
Differential Diagnosis: 1- dermal nevi may resemble nodular melanoma, 2- trauma causing them to bleed and inflame, influencing some patients to suspect malignancy. 3- telangiectatic vessels on the surface mimicking basal cell carcinoma.


Histologically Dermal Nevi are composed of nests and cords of nevus cells are found within the dermis; they may extend into the subcutaneous fat. Melanocytic cells are pale, uniform in size and are found in cords or clusters surrounded by collagen bundles in the dermis.

What are Compound Nevi

Origin: both at the dermoepidermal junction and within the dermis
Appearance: slightly or markedly raised pigmented papules
Surface: smooth or slightly papillomatous
Border: have an irregular border but are symmetric
Special features: Hair may be present, the center tends to be more heavily pigmented than the periphery, If a white halo appears at the periphery of the lesion, it is referred to as a halo nevus
Progress: tend to increase in thickness and pigmentation in late childhood and adolescence.

What are Junctional Nevi

A junctional nevus is a mole found in the junction (border) between the epidermis and dermis layers of the skin.


Nests of nevus cells cluster at the dermoepidermal junction



Onset: rare at birth and generally develop after the age of 2 years
Site: palms, soles, and the genitalia
Prevalence: most common in children
Size: vary from 0.1 to 0.6 cm
Appearance: flat or slightly raised brown to tan macules with uniform pigmentation
Surface: smooth and flat to slightly elevated
Border: round or oval and symmetric
Special features: Hairless, with preserved surface skin markings
Progress: may change into compound nevi after childhood, Degeneration into melanoma is rare.