Core Dermatology Diagnoses / CategoriesNeoplastic Benign and Malignant

Dermal melanocytosis

Author: Faculty Reviewer:

Publish date: Posted on
Last updated: May 16, 2022

Keywords #

dermal melanocytosis
benign pigmented skin lesions
Mongolian spots

Diagnosis #

Congenital dermal melanocytosis (CDM), previously called “Mongolian spots” or slate gray nevus, is a frequently encountered benign skin lesion seen in neonates and pediatric patients.[1] CDM occurs due to melanocytes in the deep dermis. At this depth, the intervening collagen scatters short wavelengths of light and the melanin produces a blue-gray color on the skin surface.[2] They tend to resolve over time.

Key Concepts #
  • CDM is a benign skin lesion occurring in neonates and infants.
  • CDM is self-limiting, typically resolving by 1-6 years of life.
  • CDM is due to arrested migration of melanocytes during fetal development, producing melanin within the dermis.
  • CDM requires no treatment.
Epidemiology #

CDM is most commonly seen in neonates and infants shortly after birth, disappearing most commonly during the first year of life and rarely persisting beyond six years of age.[3] CDM affects both sexes equally, and occurs primarily in Asian and Native American populations, occurring in 85-100% of births.[4] Among African Americans, CDM is present in >60% of births, although some studies have suggested that the number may be much higher.[4,5]Among Hispanic populations, CDM is present in 45-70% of neonates.[5,6] Among white populations, CDM occurs in less than 10% of births.[5,6]

Clinical Features #
  • Single or multiple hyperpigmented macular lesion(s) on the lower lumbar, sacral or gluteal surfaces, typically involving <5% TBSA. [1]
  • Aberrant lesions occurring on the extremities or chest. [7]
  • Pigmentation ranges from dark gray, blue, to blue-green. [1]
  • Varied shape from round, oval, and irregular. [1]
Differential Diagnoses #
  • Dermal melanocytosis
  • Nevus (including congenital melanocytic nevus)
  • Typically involves the face and orbits in a unilateral trigeminal nerve distribution
  • Associated with orbital melanocytoma
  • Nevus of Ito[8]
  • Melanocytic pigmentation involving the neck, scapular and suprascapular regions
  • Rare cases of malignant transformation
  • Non-accidental trauma[9]
  • Lesions involving atypical areas
  • Tenderness to palpation
  • Lesions in various stages of healing
Diagnostic Workup #

CDM is a benign skin lesion and is considered a clinical diagnosis, requiring no addition laboratory or histologic workup. If there is concern for Nevus of Ota, ophthalmological evaluation is required, especially if there is involvement of the sclera on physical exam.[7]

Treatment #

Treatment for CDM is not indicated in patients as it is generally self-limiting and benign, without potential for malignant transformation. For patients with extra-sacral lesions that are persistent, cosmetic treatment using laser therapy is available.[10]

References #
  1. Chua RF, Pico J. Dermal Melanocytosis. [Updated 2020 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557408/
  2. Gupta D. Mongolian spots: How important are they?. World Journal of Clinical Cases .2013; 1(8): p.230. doi: 10.12998/wjcc.v1.i8.230.
  3. Leung AK. Mongolian spots in Chinese children. Int J Dermatol. 1988 Mar;27(2):106-8.
  4. Cordova A. The Mongolian spot: a study of ethnic differences and a literature review. Clin Pediatr (Phila). 1981 Nov;20(11):714-9. doi: 10.1177/000992288102001105. PMID: 7028354.
  5. Jacobs AH, Walton RG. The incidence of birthmarks in the neonate. Pediatrics. 1976 Aug;58(2):218-22.
  6. Cordova A. The Mongolian spot: a study of ethnic differences and a literature review. Clin Pediatr (Phila). 1981 Nov;20(11):714-9.
  7. Franceschini D, Dinulos JG. Dermal melanocytosis and associated disorders. Curr Opin Pediatr. 2015 Aug;27(4):480-5.
  8. Tse JY, Walls BE, Pomerantz H, Yoon CH, Buchbinder EI, Werchniak AE, Dong F, Lian CG, Granter SR. Melanoma arising in a nevus of Ito: novel genetic mutations and a review of the literature on cutaneous malignant transformation of dermal melanocytosis. J Cutan Pathol.2016 Jan;43(1):57-63.
  9. Paul AR, Adamo MA. Non-accidental trauma in pediatric patients: a review of epidemiology, pathophysiology, diagnosis and treatment. Transl Pediatr. 2014 Jul;3(3):195-207.
  10. Kagami S, Asahina A, Uwajima Y, Miyamoto A, Yamada D, Shibata S, Yamamoto M, Masui Y, Sato S. Treatment of persistent Mongolian spots with Q-switched alexandrite laser. Lasers Med Sci. 2012 Nov;27(6):1229-32. doi: 10.1007/s10103-012-1113-4. Epub 2012 May 8. PMID: 22565344.
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