Subcutaneous Fat Necrosis of the Newborn

A boy weighing 4500 g was born at 41 weeks' gestation by Cesarean section due to fetal distress. The pregnancy was complicated by gestational diabetes. He had an Apgar score of 5 and 6 after 5 and 10 minutes, respectively. At birth, the newborn manifested respiratory distress, which needed assisted ventilation for 48 hours. He developed a convulsive attack, diagnosed as a grade 2 hypoxic-ischemic encephalopathy, which was controlled by phenobarbital. Four days later, dermatologic examination revealed subcutaneous and firm nodules, ranging from 1 to 4 cm in diameter, on the cheeks, neck, arms, legs, and back (Figure 1). Some nodules became fluctuant as abscesses. Fine-needle aspiration cytology performed on a nodule revealed a dirty background with necrotic fat-containing characteristic, radially- oriented, refractile, needle-shaped crystals (Figure 2), which was diagnosed as subcutaneous fat necrosis. The diagnosis of subcutaneous fat necrosis of the newborn was made. Laboratory studies revealed hypocalcemia at 1.65 mmol/L, hypomagnesemia at 0.48 mmol/L, and hypokalemia at 3 mmol/L. The infant received calcium, magnesium, vitamin D, and potassium supplementation. On day 18, the serum calcium increased to 3.3 mmol/L. It was associated with hypertriglyceridemia at 2.6 mmol/L. Bilateral nephrocalcinosis was detected on renal ultrasound. So, hyperhydration, diuretics, and withdrawal of vitamin D were indicated. The patient was given betamethasone 0.125 mg/kg/day for 3 weeks. After a two months course, there had been complete healing of the fat necrosis (Figure 3), normalization of the calcium and triglyceride levels, and a normal growth pattern.