Congenital dermal melanocytosis (previously referred to as Mongolian spot) is a congenital, benign, blue to gray patch caused by an increased number of dermal melanocytes. These patches are commonly seen in the sacrococcygeal area in infants of Asian or African descent but may be found on any cutaneous surface in infants of all ethnicities. The pigmentation becomes most intense at 1 year of age, reaches its peak diameter by 2 years of age, and usually fades completely by adulthood.
ICD10CM: Q82.8 – Other specified congenital malformations of skin
SNOMEDCT: 40467008 – Mongolian spot
Differential Diagnosis & Pitfalls
Child physical abuse – Childhood abuse affects children of all ages and economic and cultural backgrounds. It can often be challenging to differentiate findings attributable to child abuse from benign anogenital skin conditions. Abuse can present with purpura and ecchymoses: changes color from blue to green to brown over days to weeks, uneven pigmentation, tender to palpation. Documentation of congenital dermal melanocytosis may be helpful in avoiding any confusion.
Blue-gray spots, commonly referred to as congenital dermal melanocytosis, are large flat lesions that are usually found on the lower back or buttocks of infants at birth. They can occasionally be found on the legs or shoulders of infants, but this is less common. The color of blue-gray spots ranges from deep brown to slate gray or blue-black. They are caused by collections of pigment-producing cells (melanocytes) located in a deeper layer in the skin and are the most common type of birthmark.
Who’s At Risk
Blue-gray spots are seen in approximately 90% of African Americans and Native Americans, roughly 80% of patients of Asian descent, 70% of Hispanic patients, and between 5%-10% of white patients. Generally, male and female infants are equally affected, although some studies suggest a slightly higher incidence of these birthmarks in males. Additionally, full-term infants are more likely to have blue-gray spots than preterm infants.
Signs & Symptoms
Blue-gray spots may be single or multiple, and they range in size from a few millimeters to 10 centimeters or more in diameter. They are present at birth and, due to their appearance, can be confused for a bruise.
There is no self-care for blue-gray spots, though they naturally fade within the first years of life. In very rare cases, they persist into school age years and even into adulthood.
When to Seek Medical Care
Once the diagnosis of a blue-gray spot is made, there is essentially nothing to do except observe the spot over time and wait for resolution. If the spot does not fade within the first years of life, see your child's physician. Additionally, because this birthmark appears similarly to bruises, if you have any questions about whether or not it was present at birth, it is best to seek medical care.
There is no therapy or treatment for this diagnosis in infants because it is a harmless condition that should resolve on its own. However, large and numerous spots that persist after a year of life may be associated with rare genetic disorders in a very small number of cases. If there is a strong family history of genetic disorders along with this condition, the child's physician may decide to send blood to the lab to test for specific genetic diseases, which each have their own specific treatments.
Ashrafti MR, Shabanian R, Mohammadi M, Kavusi S. Extensive Mongolian Spots: a clinical sign merits special attention. Pediatr Neurol. 2006;34(2):143-145.
Behrman RE, Kliegman R, Jensen HB, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: WB Saunders; 2007.