Skin Moles

Congenital skin moles are present at birth and result from a proliferation of melanocytes in the dermis, epidermis, or both.

Congenital skin moles are one of several known risk factors for the eventual development of melanoma. Fortunately, melanoma remains an uncommon malignancy in prepubertal children, with an annual incidence of 0.7 cases per million children aged 0-9 years. Patient concerns regarding changing or worrisome-looking skin moles are, nonetheless, very common. Moreover, by the time a child reaches adolescence, the incidence of melanoma increases substantially, with a rate of 13.2 cases per million children aged 15-19 years. In recent years data have documented an alarming increase in melanoma in adolescents. This increase, combined with the recognition of clearly identifiable melanoma risk factors in childhood, allows physicians of the 21st century to play a crucial role in the identification of children at risk for melanoma and to aid in the prevention of melanoma through education regarding the risks of ultraviolet light exposure.

The causation of congenital skin moles remains unclear. The melanocytes of the skin originate in the neuroectoderm, although the specific cell type from which they derive remains unknown. One possible explanation for the presence of congenital skin moles is that an external insult results in a mutation that affects the morphogenesis of the embryonic neuroectoderm and migration of precursor cells to the skin.

Congenital skin moles have been classified into three groups according to size. Small skin moles are less than 1.5 cm in greatest diameter, medium skin moles are 1.5-19.9 cm in greatest diameter, and large or giant skin moles are greater than 20 cm in greatest diameter.

A rare congenital syndrome characterized by the presence of congenital skin moles and melanotic neoplasms of the central nervous system. The current diagnostic features for neurocutaneous melanosis are (1) large (more than 20 cm) or multiple (more than 3) congenital skin moles in association with meningeal melanosis or melanoma, (2) no evidence of meningeal melanoma except in patients in whom cutaneous lesions are histologically benign, and (3) no evidence of cutaneous melanoma except in patients in whom meningeal lesions are histologically benign.

Neurocutaneous melanosis may result from an error in the morphogenesis of the neuroectoderm, which gives rise to the melanotic cells of both the skin and meninges. Clinically, patients may present with increased intracranial pressure due to hydrocephalus or a mass lesion. The prognosis of patients with symptomatic neurocutaneous melanosis is very poor, even in the absence of malignancy.

Congenital skin moles are present in 1-2% of newborn infants.

Congenital skin moles, depending on size and location, may have a significant impact on cosmesis. Giant congenital skin moles place individuals at an increased risk for the development of melanoma at the site of the mole. For giant congenital skin moles, the risk of developing melanoma has been reported to be as high as 5-7% by age 60 years. One study suggests that the risk of melanoma may be greater in those with giant congenital skin moles with more satellite lesions or a larger diameter. However, while the general consensus regarding smaller skin moles is that they pose a greater risk for the development of melanoma than normal skin, this risk has not been quantified.

No racial predilection is recognized.

Congenital skin moles occur in both sexes, with no known predilection.

To be considered congenital skin moles, lesions must be present at birth.

skin moles may be located anywhere on the body. Classification as a congenital mole depends in large part on an accurate history or photographs or medical reports from birth.

Biopsy confirms a benign or malignant nature in suggestive lesions.

In cases associated with a high index of suspicion for the presence of neurocutaneous melanosis, magnetic resonance imaging of the central nervous system is a useful diagnostic tool.

Dermoscopy usually reveals a heterogenous globular pattern.

Because of the increased risk of melanoma associated with congenital skin moles, attempts have been made to distinguish congenital skin moles from acquired skin moles on the basis of histology. Distinguishing histologic features include (1) involvement by nevus cells of deep dermal appendages and neurovascular structures (including hair follicles, sebaceous glands, arrector pili muscles, and within walls of blood vessels), (2) extension of nevus cells to deep dermis and subcutaneous fat, (3) infiltration of nevus cells between collagen bundles, and (4) a nevus cell–poor subepidermal zone (Mark, 1973; Rhodes, 1985; Everett, 1989). In contrast to congenital skin moles, acquired skin moles are usually composed of nevus cells that are limited to the papillary and upper reticular dermis and do not involve the appendages.

The management of congenital skin moles depends on a number of factors, including the size of the lesion, the location of the lesion, the age of patient, the effect on cosmesis, and the potential for malignant transformation.

Although the risk of malignant transformation in small and medium-sized congenital skin moles has not been established, many physicians agree that the risk is probably not significant enough to warrant the prophylactic removal of all of these lesions. However, some patients may desire removal of these lesions to improve cosmesis. Until evidence is presented on which to base definitive treatment guidelines, many physicians are managing small and medium-sized congenital skin moles with baseline photography and regular follow-up.

Surgical removal of congenital skin moles is performed for 2 main reasons, (1) to improve the cosmetic appearance of the patient and (2) to reduce the likelihood of malignant transformation. The increased risk of malignant transformation associated with giant congenital skin moles is well established. Ideally, these lesions are removed whenever possible. Barriers to removal may include the size of the lesion and its proximity to vital structures. Several different procedures are available to remove these moles.

Surgical excision of giant congenital skin moles, depending on the size and location of the lesion, may be challenging. Often, the size of the lesion necessitates a staged excision. Tissue expanders, tissue grafts, and tissue flaps are often necessary to close the large defects following excision. Because the melanocytes in such cases may extend deep into underlying tissues (including muscle, bone, and central nervous system), removing the cutaneous component may not eliminate the cancerous risk.

Laser treatment of the lesions has been performed with a number of different types of lasers. Because of the lack of penetrance to deeper tissue levels, long-term recurrence is also an issue with these techniques.

No specific dietary recommendations are necessary for patients with congenital skin moles.

No specific activity restrictions are necessary for patients with congenital skin moles. However, because of the increased risk for the development of melanoma, especially in patients with giant congenital skin moles, proper protective measures should be taken to minimize ultraviolet light exposure. Maintaining the ability to take part in normal activities should be a consideration when planning surgical removal of a congenital nevus.

Patients with giant congenital skin moles have an increased risk of developing melanoma (as high as 5-7% by age 60 y). The lifetime risk of malignant transformation associated with smaller skin moles is surely smaller than that for giant skin moles but is unknown at this time.

The prognosis for patients with small or medium-sized congenital skin moles is good. Although the risk of developing melanoma in these lesions has not been quantified, it is generally regarded as only slightly higher than that of normal skin. Despite the increased risk for melanoma in patients with giant congenital skin moles, the vast majority of patients never develop melanoma. Therefore, prognosis remains good in these patients, especially if the lesions are examined regularly for signs of atypia.

Prognosis in cases of symptomatic neurocutaneous melanosis is quite poor.

All people need to be educated on the importance of protection from ultraviolet light exposure. This is especially important in people who have congenital skin moles, particularly the giant type, because they are already at an increased risk for the development of melanoma.