Puzzling pigmentation on a baby’s scalp

February 1, 2015

A healthy 2-month-old girl presents for evaluation with a large pigmented plaque on her left cheek and scalp that her mother says she has had since birth.

THE CASE

A healthy 2-month-old girl presents for evaluation with a large pigmented plaque on her left cheek and scalp that her mother says she has had since birth.

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DERMCASE diagnosis:  CONGENITAL MELANOCYTIC NEVUS

Small congenital melanocytic nevi (CMN) are present in approximately 1% of newborn infants. Congenital pigmented nevi larger than 9.9 cm in diameter occur in 1 per 20,000 newborns and those larger than 20 cm in diameter occur in 1 per 500,000.1,2

Congenital pigmented nevi have been categorized based on diameter as small (<2 cm); medium (1.5-19.5 cm); and large or giant congenital nevi (>20 cm in adolescents or predicted to reach 20 cm by adulthood).3,4 Giant nevi also have been described by using the prediction classification as comprising 9 cm on a child’s head and 6 cm on a child’s body.5 Giant nevi frequently lie in the distribution of a dermatome and will cover areas such as an arm, leg, head, or a significant part of the trunk.6 These lesions are usually described as coat-sleeve, stocking, bathing-trunk, or giant hairy nevi.

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The lifetime risk of melanoma arising in small and medium congenital nevi is unknown but undoubtedly is less than 1%. The risk in large congenital nevi is also unknown and estimated at 2% to 4%. The risk in giant nevi is thought to be greatest during the first decade of life, in children with more than 20 satellite nevi, and in patients with associated leptomeningeal melanosis or nevus involving the central nervous system (CNS).7,8

The risk of leptomeningeal involvement is thought to be highest in children with giant CMN involving the scalp, back of the neck, and midline of the back. These patients may present in the first 2 years of life with increased intracranial pressure and/or spinal cord compression. High-risk infants should have a neurologic evaluation with diagnostic magnetic resonance imaging (MRI) and cerebrospinal fluid cytology for early detection of neurologic manifestations of CMN.9-11

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The management of giant congenital nevi remains controversial and depends on the size and location of the lesion; the age of the patient; and the possibility of malignant transformation.

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Experts agree that whenever possible, and as a prophylactic measure, large congenital nevi should be totally excised with careful histologic evaluation of the lesion.12 Unfortunately, total excision is usually impossible, so long-term monitoring of skin lesions as well as growth and development are important. Although the risk of malignant changes in small- and medium-sized lesions is small and monitoring without surgical intervention is reasonable in most cases, psychosocial factors may require excision of these lesions.

Outcome

The infant in this case was healthy with normal growth and development and no signs of CNS involvement. The patient’s CMN measured 9 cm by 11 cm and was associated with dark brown satellite nevi on the back, legs, and right shoulder, ranging from 1 cm to 3 cm in diameter. She was referred to dermatology and neurology where she had a neurologic evaluation and MRI of the brain and cervical spine that were unremarkable. She is currently following regularly with both dermatology and neurology.

 

REFERENCES

1. Castilla EE, da Graça Dutra M, Orioli-Parreiras IM. Epidemiology of congenital pigmented naevi: I. Incidence rates and relative frequencies. Br J Dermatol. 1981;104(3):307-315.

2. Quaba AA, Wallace AF. The incidence of malignant melanoma (0 to 15 years of age) arising in "large" congenital nevocellular nevi. Plast Reconstr Surg. 1986;78(2):174-181.

3. Nevi and malignant melanoma. In: Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. Edinburgh: Mosby; 2004:776-777.

4. Bittencourt FV, Marghoob AA, Kopf AW, Koenig KL, Bart RS. Large congenital melanocytic nevi and the risk for development of malignant melanoma and neurocutaneous melanocytosis. Pediatrics. 2000;106(4):736-741.

5. Bauer BS, Corcoran J. Treatment of large and giant nevi. Clin Plast Surg. 2005;32(1):11-18, vii.

6. Hurwitz S. Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 2nd ed. Philadelphia, PA: Saunders; 1993:203-206.

7. Rhodes AR, Sober AJ, Day CL, et al. The malignant potential of small congenital nevocellular nevi. An estimate of association based on a histologic study of 234 primary cutaneous melanomas. J Am Acad Dermatol. 1982;6(2):230-241.

8. Egan CL, Oliveria SA, Elenitsas R, Hanson J, Halpern AC. Cutaneous melanoma risk and phenotypic changes in large congenital nevi: a follow-up study of 46 patients. J Am Acad Dermatol. 1998;39(6):923-932.

9. Amer A, Fischer H. Giant congenital melanocytic nevi. Clin Pediatr. 2008; 47(8):824-826.

10. DeDavid M, Orlow SJ, Provost N, et al. Neurocutaneous melanosis: clinical features of large congenital melanocytic nevi in patients with manifest central nervous system melanosis. J Am Acad Dermatol. 1996;35(4):529-538.

11. Kadonaga JN, Frieden IJ. Neurocutaneous melanosis: definition and review of the literature. J Am Acad Dermatol. 1991;24(5):747-755.

12. The management of congenital nevocytic nevi. Pediatr Dermatol. 1984;2(2):143-156.

Dr Amer is associate professor of pediatrics, Carman and Ann Adams Department of Pediatrics, Wayne State University School of Medicine and Children’s Hospital of Michigan, Detroit. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. The author and section editor have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to focus on key teaching points. Images also may be edited or substituted for teaching purposes.