Subcutaneous fat necrosis of the newborn.

We report on a term girl born by urgent caesarean section due to variable foetal decelerations during labour. Weight 3830 g, Apgar scores 4/6/8 (1’/5’/10’) and arterial umbilical cord pH 6.89. Suffering a mild respiratory distress syndrome for the first day of life with a maximum FiO2 of 0.3, she was transferred to the neonatal intensive care unit. Transient arterial hypotension down to 29 mm Hg mean arterial pressure was rapidly corrected by two intravenous bolus administrations of 0.9% saline solution. Initially the capillary blood gases showed metabolic acidosis (pH 7.14, pCO2 30 mm Hg, BE –18 mmol/l), but recovered completely and spontaneously within 12 hours of life. No body surface cooling was applied. The neurological findings after 24 hours of life were normal and breastfeeding was started on day 2 without problems. Cranial ultrasound including doppler studies on day 2 revealed no signs of cerebral oedema or bleeding. The child was discharged to maternity in good health on day 5, but was readmitted on day 6 with obviously painful, firm, large erythematous nodules and plaques on her back, dorsal neck and upper arms (fig. 1). She was placed in the prone position and received paracetamol. Histological examination of a biopsy specimen from a nodule on her back revealed patchy fat necrosis with fat crystallisation. In addition, macrophages and foreign-body giant cells, neutrophils, lymphocytes and eosinophils were present in the inflammatory infiltrate (fig. 2). These findings were consistent with the diagnosis of subcutaneous fat necrosis of the newborn (SCFN). Additional diagnostic workup showed normal serum calcium levels of 2.2–2.6 mmol/l (1.3–1.6 mmol/l ionised calcium), no thrombocytopenia and no hyperlipidaemia. Starting on day 16, the cutaneous lesions gradually decreased in size and intensity, were less erythematous and no longer painful. The newborn was finally discharged home. At 12 weeks of age the cutaneous symptoms had resolved. She did not develop hypercalcaemia in the first year of life and neurological follow-up was excellent.