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(Photo contributor: Binita R. Shah, MD)

*The authors acknowledge the special contributions of Binita R. Shah, MD, to prior edition.


Clinical Summary

Congenital dermal melanocytosis (also referred to as Mongolian spots or blue-gray macules of infancy) is the most frequently encountered birthmark in neonates. Melanin-containing melanocytes in the dermis are present (migrational arrest), and the distinctive blue color, characteristic of dermal melanin, occurs as a result of the Tyndall effect (when light strikes the surface of the lesion, red wavelengths of light are absorbed and blue wavelengths are reflected back from the brown melanin pigment from the dermis). Mongolian spots are more prevalent in Asian (40% to >80%), African American (30% to >60%), Hispanic (25%–70%), and Native American infants than in white infants (<10%). The skin lesion is flat (macular), slate-gray, greenish-blue or brown, and consists of poorly circumscribed, single or multiple lesions ranging in size from a few millimeters to several centimeters. The most common location are the sacrum and buttocks (90%), but lesions may occur anywhere, including the back, shoulders, or flank. Mongolian spots fade gradually and resolve by age 5 to 6 years in about 96% of cases. Differential diagnosis of Mongolian spots includes accidental or inflicted injury and other forms of dermal melanocytosis (eg, nevus of Ito or Ota; See Figures 2.13, 2.14, 2.15).


Congenital Dermal Melanocytosis (Mongolian Spots). (A) Bluish-gray macular lesions, present since birth, are seen on the back and buttocks (the most common location) of an otherwise healthy African American infant. (B) Lesion on the anterior chest wall in the same infant. (Photo contributor: Binita R. Shah, MD.)


Congenital Dermal Melanocytosis (Mongolian Spot). Multiple areas of bluish discoloration are seen on the back and buttocks in a Caucasian infant, in whom the incidence of Mongolian spots is uncommon (<10%), and these lesions may be mistakenly attributed to inflicted bruises. (Photo contributor: Binita R. Shah, MD.)


Congenital Dermal Melanocytosis (Mongolian Spot). A 4-year-old child with bruise-like discoloration on his right forearm. He also had several similar blue-gray lesions on his lower sacral area (typical distribution). These lesions have been present since birth. (Photo contributor: Julie Cantatore-Francis, MD.)


Congenital Dermal Melanocytosis (Mongolian Spot). An infant brought to the ED in cardiopulmonary arrest had these lesions thought to be Mongolian spots; however, inflicted bruises from child abuse were in the differential diagnosis. The medical examiner ...

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