Lesions are clean, sharply demarcated, and noninflammatory in appearance. Over 500 cases have been reported since it was described, but due to significant underreporting of this generally benign disorder, precise frequency is unknown. Small underlying bony defects usually close spontaneously during the first year of life. Surgical repair of large or multiple scalp defects may be considered with excision and primary closure, if feasible, or with the use of tissue expanders and rotation of a flap. Truncal and limb defects, despite large size, usually epithelialize and form atrophic scars, which can later be revised if necessary.
Major complications are rare but include hemorrhage, secondary local infection and meningitis.
There is no racial predilection. There is no sexual predilection. Diagnosis is made on the basis of physical findings indicative of an in utero disruption of skin development. Most lesions occur on the scalp lateral to the midline, but may also occur on the face, trunk, or limbs, sometimes symmetrically. Lesions are noninflammatory and well-demarcated.