مرکز بهداشت امام محمد باقر- Mongolian spot-Patient X [Mongolian spot] Mongolian spots (MS) are grayish-blue macules that typically present in the lumbosacral and gluteal regions of newborns. They are mostly benign and tend to resolve with age. Mongolian spot typically disappears spontaneously within 4 years but can persist for life. Mongolian spot is a congenital, developmental condition exclusively involving the skin. Mongolian spot results from entrapment of melanocytes in the dermis during their migration from the neural crest into the epidermis Incidence: 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. 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). So! Mongolian spots are pretty harmless with good prognosis and normally self-resolving, however there are some rare exceptions: • large sizes (>10 cm), extra sacral location, dark-colored lesions, and multiple patches are more likely to persist beyond 1 year. It is postulated that infants with Mongolian spots persisting beyond age 1 year might be at increased risk for inborn errors of metabolism. (Gupta And Thapa) • Mongolian spots have been associated with cleft lip, spinal meningeal tumor, melanoma, phakomatosis pigmentovascularis types 2 and 5, and Sjögren-Larsson syndrome (One case report) REMEMBER: Keep in mind other differential diagnoses like child abuse when considering a patient with a possible Mongolian spot Other ddx : blue nevi, Dermal melanocyte hamartoma, Nevi of Ota and Ito References: https://ijdvl.com/mongolian-spots/ Incidence of Mongolian spots and its common sites at two university hospitals in Tehran, Iran. (medscape.com) Congenital Dermal Melanocytosis (Mongolian Spot) Clinical Presentation: History, Physical Examination (medscape.com) [Combined naevus flammeus and naevus fuscocoeruleus: phacomatosis pigmentovascularis type IIa]. (medscape.com) [A new variety of neurocutaneous melanosis: benign leptomeningeal melanocytoma associated with extensive Mongolian spot on the back]. (medscape.com) Cleft lip mongolian spot: mongolian spot associated with cleft lip. (medscape.com) The Mongolian spot: a study of ethnic differences and a literature review. (medscape.com) .