Congenital Dermal Melanocytosis (Mongolian Spot) 

Updated: Mar 22, 2019
Author: Abdul-Ghani Kibbi, MD; Chief Editor: Dirk M Elston, MD 

Overview

Background

Mongolian spot refers to a macular blue-gray pigmentation usually on the sacral area of healthy infants. Mongolian spot is usually present at birth or appears within the first weeks of life. Mongolian spot typically disappears spontaneously within 4 years but can persist for life.

Pathophysiology

Mongolian spot is a congenital, developmental condition exclusively involving the skin.[1, 2] Mongolian spot results from entrapment of melanocytes in the dermis during their migration from the neural crest into the epidermis. This migration is regulated by exogenous peptide growth factors that work by the activation of tyrosine kinase receptors. It is postulated that accumulated metabolites such as GM1 and heparan sulfate bind to this tyrosine kinase receptor and lead to severe neurologic manifestations and aberrant neural crest migration.

Etiology

Mongolian spot is a hereditary developmental condition caused by entrapment of melanocytes in the dermis during their migration from the neural crest into the epidermis.

It was discovered in extensive dermal melanocytosis associated with phakomatosis pigmentovascularis that activating mutations in GNA11 and GNAQ, genes that encode Gα subunits of heterotrimeric G proteins, occur, indicating this condition belongs to the group of mosaic heterotrimeric G-protein disorders.[3]

Epidemiology

Frequency

United States

More than 90% of Native Americans, 80% of Asians, and 70% of Hispanics have Mongolian spots; less than 10% of whites have Mongolian spots. A recent study on the prevalence of birthmarks and transient skin lesions in 1000 Spanish newborns conducted at a neonatal clinic has revealed a proportion of 0.189 for Mongolian spots, with a confidence interval of 0.164-0.213.[4]

More recently, a prospective clinical study of cutaneous findings in newborns in the United States has shown an overall incidence of 14% for dermal melanocytosis over the sacrum and buttocks. When these patients were analyzed according to ethnicity, the incidence was 29% in Asians, followed by others (unspecified ethnicity), Hispanics, African Americans, and whites.[5]

International

The prevalence of Mongolian spots varies among different ethnic groups. This condition is most common among Asians. Mongolian spot has also been reported in 80% of East African children, in 46% of Hispanic children, and in 1-9% of white children.[6]

The incidence of Mongolian spot was not significantly associated with sex, gestational age, mother's age group, or delivery type at 2 hospitals in Iran. However, in one of the hospitals in which this observational study was done, mongolian spots were shown to be significantly associated with a high birth weight (≥2500 g).[7]

In cross-sectional study on 203 healthy neonates in a Brazilian public hospital, a greater incidence was found in nonwhite, black, and Asian babies.[8]

A case-controlled study conducted in Turkey on 50 patients with Down syndrome showed that Mongolian spot was among the most common mucocutaneous disorders; it was seen in 22% of patients and in 6% of healthy controls with a P -value of 0.018.[9]

Race

Mongolian spots are observed in more than 90% of infants of the Mongoloid race (ie, East Asians, Indonesians, Polynesians, Micronesians, Amerindians, Eskimos).

Sex

No sex predilection is reported for Mongolian spot.

Age

Mongolian spot is usually present at birth, but it can also appear within the first weeks of the neonatal period.

Prognosis

Mongolian spots usually fade in the first year of life, but, at times, they may persist indefinitely. However, melanocytes may persist in the dermis when examined histologically.[10] Aberrant Mongolian spots located in areas distal from the lumbosacral region may persist, unlike the typically located ones, which have a tendency to resolve.[11]

Gupta and Thappa followed 1524 infants with Mongolian spots and found that 42% of these lesions disappeared completely by age 1 year. They demonstrated that large sizes (>10 cm), extrasacral location, dark-colored lesions, and multiple patches are more likely to persist beyond 1 year. The authors also postulated that infants with Mongolian spots persisting beyond age 1 year might be at increased risk for inborn errors of metabolism.[12]

Mongolian spot is not associated with mortality or morbidity. However, three cases of congenital aplasia cutis were reported by Japanese authors in concomitance with dermal melanocytosis, but not with the typical distribution of the Mongolian spot, in two males and one female.[13, 14]

 

Presentation

History

In Mongolian spot, an asymptomatic bluish discoloration overlying the sacrococcygeal area is present at birth.

Physical Examination

Mongolian spots consist of blue-gray macular pigmentation. The distinctive skin discoloration is due to the deep placement of the pigment in the dermis, which imparts a bluish tone to the skin from the Tyndall effect of scattered light (see the image below).

Multiple Mongolian spots in a child. Multiple Mongolian spots in a child.

Typically, it is a few centimeters in diameter, although much larger lesions also can occur. Lesions may be solitary or numerous. Most commonly, Mongolian spot involves the lumbosacral area, but the buttocks, flanks, and shoulders may be affected in extensive lesions. Noteworthy is that in Gupta’s and Thappa’s study, the majority of Mongolian spots were in the sacral area, blue-green or dark blue, smaller than 5 cm, and irregularly shaped. The lower extremity, upper back, upper extremity, groin, shoulder, and chest were other locations, in decreasing order of frequency.[12]

Generalized Mongolian spots involving large areas covering the entire posterior or anterior trunk and the extremities have been reported.

Several variants exist, as follows:

  • Persistent Mongolian spots are larger, have sharper margins, and persist for many years.[15]

  • Aberrant Mongolian spots involve unusual sites such as the face or extremities.[16, 17, 18, 19]

  • Persistent aberrant Mongolian spots also are referred to as macular-type blue nevi.

  • Superimposed Mongolian spots, in which a darker Mongolian spot overlies a lighter one, have been described.[20]

Mongolian spots have been associated with cleft lip,[21] spinal meningeal tumor, melanoma,[22] phakomatosis pigmentovascularis types 2 and 5,[23, 24, 25, 26, 27, 28] and Sjögren-Larsson syndrome (one case report).[29] A few cases of extensive Mongolian spots have been reported with inborn errors of metabolism, the most common being Hurler syndrome,[30] followed by GM1 gangliosidosis type 1,[31, 32] Niemann-Pick disease, Hunter syndrome,[33, 34] mannosidosis,[35] Wolf-Hirschhorn syndrome,[36] and, very rarely with Sandhoff disease.[37] In such cases, the Mongolian spots are likely to persist/progress rather than resolve.

A case report described a 15-month-old Azerbaijani girl with extensive, presumably systemized, Mongolian spots over her neck, back, shoulder, buttocks, and limbs, without facial involvement except for bilateral sclerae and choroidal areas.[38]

A unique case of phacomatosis pigmentovascularis with nevus of Ota, extensive Mongolian spot, nevus flammeus, nevus anemicus, and cutis marmorata telangiectatica congenita has been described and may represent a new variant of phacomatosis pigmentovascularis.[39, 40] Other additional sporadic cases of extensive Mongolian spots in association with various types of phacomatosis pigmentovascularis have been reported in the literature, the most recent of which is a 5‐year‐old girl whose phacomatosis pigmentovascularis was unclassifiable and represented a novel combination of a pigmented lesion accompanying capillary malformation.[41]

A halolike response has been described around a café-au-lait spot superimposed on Mongolian spot in an 8-month old infant with neurofibromatosis type I and in a 5-month-old baby, without any evidence of a genetic disorder or systemic disease.[42, 43]

 

DDx

Diagnostic Considerations

Consider child abuse; owing to their color, Mongolian spots may be mistaken for bruises, especially when located on atypical sites.[44]

Also consider dermal melanocyte hamartoma.[45]

Differential Diagnoses

 

Workup

Laboratory Studies

Usually, laboratory studies are not indicated except when extensive Mongolian spots are present. In these circumstances, it is advisable to evaluate the patient for inborn errors of metabolism in order to avoid irreversible organ damage.[46]

Imaging Studies

In extensive Mongolian spots involving the back, radiographic studies are needed to rule out a spinal meningeal tumor or anomaly.

Histologic Findings

Dendritic melanocytes with variably pigmented melanosomes typically are located in the deep reticular dermis. The melanocytes usually are oriented parallel to the epidermis. In contrast, the melanocytes in blue nevi are denser in number and more focally aggregated.

 

Treatment

Medical Care

Opaque cosmetics may be used as camouflage for Mongolian spots.

Surgical Care

The value of lasers in Mongolian spot is uncertain. However, in a retrospective study of 26 Japanese patients, the Q-switched alexandrite laser showed better outcomes in extrasacral lesions treated at a younger age.[47] The Q-switched ruby laser was used in the treatment of aberrant mongolian spots in 53 patients; it was more effective in exposed areas versus nonexposed areas.[11]

Intense pulsed light is also an effective method for the treatment of aberrant Mongolian spots.[48] . More recently, novel picosecond 755-nm alexandrite and 1064-nm Nd:YAG lasers have been used on three cases of ectopic Mongolian spots and one case of persistent Mongolian spot, with efficacious results after one treatment session and with minimal adverse events.[49]