A full-term 1-day-old boy weighing 3140 g was transferred to our tertiary care children’s hospital with large areas of skin defects on his scalp, trunk, and extremities. His parents were nonconsanguineous, and the results of prenatal maternal laboratory screening for human immunodeficiency virus, hepatitis B, group B streptococci, and rapid plasma reagin were negative. Intrauterine fetal death of a twin had been reported at 16 to 18 weeks of gestation. No other complications were noted during the pregnancy. On physical examination, a full-thickness ulcer of the scalp vertex was observed extending from the anterior fontanel to the posterior fontanel in an area overlying the sagittal sinus. The defect measured 5 7 cm and revealed exposed dura and subcutaneous vessels (Figure 1). Two symmetric, vertically oriented, full-thickness defects, each measuring 3.2 cm, with minimal surrounding erythema, were noted on the lateral aspect of the abdomen (Figure 2). Examination of the knees revealed symmetric full-thickness defects that appeared as yellow-red, indurated ulcers. Symmetric, linear scars were observed bilaterally in the axillary and inguinal creases. Magnetic resonance imaging of the head and a magnetic resonance venogram revealed patent major intracranial venous sinuses and slight hypoplasia of the left transverse sinus (considered a normal congenital variation). A relative lack of subcutaneous fat over the superior aspect of the skull was also observed, consistent with the clinical presentation. Concern that the extensive open defect posed a high risk for sagittal sinus thrombosis, hemorrhage, or meningitis prompted plastic surgery and neurosurgery consultations. The scalp defect was repaired by plastic surgery with a skin graft, while the remaining areas of aplasia cutis congenita were allowed to heal by secondary intention. Over the next 3 weeks, the scalp healed well, without complications, as did the other areas of aplasia on the abdomen and knees. DIAGNOSTIC CHALLENGE