Mongolian spots--a prospective study.

To determine the frequency and clinical presentation of Mongolian spots (MS) and assess their evolution with age, this study was conducted in three phases. The first phase examined 2,313 babies born at Jawaharlal Institute of Postgraduate Medical Education and Research between October and December 2010 for the number, size, shape, color, and distribution of MS. Babies with MS were followed up at 6 months and 1 year, in the second and third phases, respectively, to note the evolution of the patches. Of 2,313 babies, 1,524 (65.9%) had MS. The majority had a single patch (n = 790), measuring less than 5 cm (n = 932), with an irregular shape (n = 981) and a blue-green color (n = 577). The most common site was sacral (n = 1,203), and the most common extrasacral site was a lower extremity (n = 156). A single case of superimposed MS was recorded. Male sex and prematurity were significantly associated with MS (p < 0.05). At 6 months, 73 of 634 babies (11.5%) showed fading and 83 (13.1%) showed complete disappearance. At 1 year, 90 (14.2%) showed fading and 268 (42.3%) showed complete disappearance. Multiple MS (p < 0.05), extrasacral position (p < 0.05), size larger than 10 cm (p < 0.05), and dark-colored lesions (blue/blue-black) (p < 0.05) were significantly associated with persistence beyond 1 year. Seven hundred ninety babies (51.8%) had a single MS. More than 40% of MS disappeared by 1 year. Multiple patches, extrasacral position, size larger than 10 cm, and dark-colored lesions were markers of persistence beyond 1 year.