Is the therapeutic hypothermia main cause of subcutaneous fat necrosis of newborn?
Dear Editor, We read with great interest the article by Fumagalli et al.,1 who reported subcutaneous fat necrosis (SFN) in an infant suffering perinatal hypoxic injury and treated with total body cooling, which complicated by hypercalcaemia. In their report,1 it is suggested that total body cooling likely increase the risk of SFN and renal complications. Recently, we report a case of SFN, which complicated by hypercalcaemia, due to perinatal hypoxic injury.2 Unlike case of Fumagalli et al.,1 our patient did not undergo to hypothermia therapy. Hence, we would like to make some comments on their report. Firstly, it is reported that as if SFN is mainly caused by therapeutic hypothermia in newborns. Although the hypothermia can cause to SFN,3 it usually occurs secondary to some perinatal conditions about by postnatal day five to seven.2 However, cold panniculitis appears 48 to 72 hours after exposure to cold.4 Therefore, in case of Fumagalli et al.,1 SFN at 35 hour of life suggests the facilitating effect of cold stress. Nevertheless, it should be emphasized that neonatal SFN is primarily caused by perinatal asphyxia,1,2 but therapeutic hypothermia may facilitate this process. Secondly, marked nephrocalcinosis present in this case may suggest prolonged severe hypercalcaemia. We wonder if the patient's kidneys previously evaluated by ultrasound for any reason? As hypercalcaemia is an expectant metabolic complication of SFN of newborn,1,2 these patients should be closely monitored for development of hypercalcaemia, as reported in present case. Nephrocalcinosis present in this case is due to hypercalcaemia as a complication SFN, but not being hypothermia therapy. However, although the hypothermia may cause renal damage,5 hypoxic- ischemic injury itself is the main cause of renal injury in these cases. Therefore, title of the article in which "Total body cooling: skin and renal complications" is not consistent with the reported case. In conclusion, SFN of the newborn is a disorder of the adipose tissue, mostly affecting full-term or post-term infants who experience perinatal distress. Nevertheless, though perinatal hypoxic-ischemic event is the main cause of SFN, hypothermia may facilitate its development. In addition, the patients with SFN should be closely monitored for developing metabolic problems like hypercalcaemia.
REFERENCES 1. Fumagalli M, Ramenghi LA, Pisoni S, Borzani I, Mosca F. Total body cooling: skin and renal complications. Arch Dis Child Fetal Neonatal Ed 2011;DOI: 10.1136/adc.2010.207886 2. Hakan N, Aydin M, Zenciroglu A, et al. Alendronate for the treatment of hypercalcaemia due to neonatal subcutaneous fat necrosis. Eur J Pediatr 2011;DOI: 10.1007/s00431-011-1468-8 3. Markus JR, de Carvalho VO, Abagge KT, et al. Ice age: a case of cold panniculitis. Arch Dis Child Fetal Neonatal Ed 2011;96:F200. 4. Torrelo A, Hern?ndez A. Panniculitis in children. Dermatol Clin 2008;26:491-500, vii. 5. Ura H, Asai Y, Mori K, Nara S, Yoshida M, Itoh Y. Total necrosis of the pancreas and renal cortex secondary to hypothermia therapy. J Trauma 2002;52:987-9.
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