Subcutaneous fat necrosis of the newborn: a systematic evaluation of risk factors, clinical manifestations, complications and outcome of 16 children.

Background: Subcutaneous fat necrosis (SFN) of the newborn is a rare acute transient hypodermatitis that develops within the first weeks of life in term infants. It often follows a difficult delivery. Prognosis is generally good except for the development of hypercalcaemia in severe cases. Only several case reports or small patients series have been published.

Objectives: To evaluate risk factors, complications and outcomes of SFN in 16 consecutive patients seen from 1996 to 2002 in our Department of Paediatric Dermatology.

Methods: On a case-report form created for the study, we recorded putative risk factors concerning the mother, pregnancy and delivery, clinical aspects of SFN, and early and late outcomes. The study was conducted in two stages: the first was a retrospective analysis of the observations and the second analysed data collected on children and their parents during a new consultation (n=10).

Results: All the children were born at term. Lesions appeared a mean of 4 days after delivery. Three-quarters of the children had diffuse SFN. Risk factors identified were newborn failure to thrive (12/16), forceps delivery (7/16), maternal high blood pressure (3/10) and/or diabetes (2/10), and newborn cardiac surgery (1/16). Putative novel risk factors were macrosomia (7/16), exposure to active (4/10) or passive (3/10) smoking during pregnancy, putative or known maternal, paternal or newborn risk factors for thrombosis (5/10), and dyslipidaemia (2/10). Complications were hypercalcaemia (9/16), pain (4/16), dyslipidaemia (1/16), renal insufficiency (1/16) and late subcutaneous atrophy (6/6).

Conclusions: This study on 16 newborns with SFN provides new information. Familial or newborn risk factors for thrombosis are frequent. Macrosomia, familial dyslipidaemia and smoking should be evaluated. The main complications identified were severe pain, hypercalcaemia and subcutaneous atrophy.