Mongolian spots are very common bluish-gray stains that are typically seen on the lower back of darker skinned newborns (Fig. 1.22).

Lesions occur in >90% of African-American neonates, 60% to 70% of Asian and Hispanic neonates but are only seen in <10% of Caucasian babies.

The cause is unknown, but represents a collection of spindle-shaped melanocytes located deep in the dermis.

Presents at birth as a flat, deep brown to slate gray or blue-black, ill-defined large flat (macular) lesions.

There can be single or multiple lesions that often coalesce into larger lesions.

The borders are usually irregular and occasionally indistinct.

Most commonly located on the lumbosacral areas and buttocks; occasionally seen on the lower limbs, back, flanks, and shoulders.

Sometimes can be widespread and extensive (Fig. 1.23).

Lesions tend to fade during first 2 to 3 years of life.

Occasionally, persist into adulthood.

The diagnosis is clinical.