epidermolysis bullosa Antithyroid drugs, most notably methimazole, have been implicated in some cases of aplasia cutis congenita Indurated Plaques Subcutaneous Fat Necrosis Subcutaneous fat necrosis is a condition seen in usually term infants with the development of freely mobile nodules and plaques with or without redness They usually appear within the first weeks of life and are usually limited to areas of trauma or ischemia during delivery These can be asymptomatic or mildly tender Risk factors include high birth weight, prolonged labor, neuroprotective cooling, and other ischemia The most common locations are the back, buttocks, and cheeks Lesions resolve spontaneously in weeks to months Mild atrophy of the skin may be noted after resolution Complications include hyper- or hypocalcemia, lactic acidosis, high levels of ferritin, and transient thrombocytopenia; hypercalcemia is the most common For extensive lesions, serum calcium, phosphorus, parathyroid hormone, and vitamin D levels should be monitored and patients should be observed closely for irritability, vomiting, anorexia, renal failure, or failure to thrive in the first months Pamidronate and low-calcium formula are used in severe cases In most cases, reassurance is all that is needed Vascular Patches/Plaques and Hamartomas Acute Hemorrhagic Edema of Infancy Acute hemorrhagic edema of infancy is a distinctive, cutaneous small-vessel leukocytoclastic vasculitis of young children Dark purple or pink in color, somewhat annular patches and plaques, without surface change, occur mostly on the face and extremities ( Fig 69.14 ) Infants otherwise look well and are usually afebrile or at most have a low-grade fever Visceral involvement is uncommon, and spontaneous recovery usually occurs within to weeks without sequelae The main differential diagnosis is Henoch–Schönlein purpura