Subcutaneous fat necrosis, a rare but serious side effect of hypoxic-ischemic encephalopathy and whole-body hypothermia

Objective: To describe the clinical characteristics and risk factors in infants with subcutaneous fat necrosis (SFN) following therapeutic hypothermia for hypoxic-ischemic encephalopathy (HIE). Methods: A case-control study was performed by a retrospective chart review of infants with moderate or severe HIE admitted to a level IV regional perinatal center and who underwent whole-body cooling. Results: A total of 14 (8.1%) of 171 infants with moderate or severe HIE who underwent whole-body cooling developed SFN during hospitalization. There were more females [71% (10/14)] and large-for-gestational age (LGA) infants [28% (4/14)] in the SFN group vs. 36% females (57/157) and 8% LGA infants (13/157) in the group without SFN (P-values of 0.009 and 0.015, respectively). The mean lowest platelet count was lower 108 ± 55 10⁹/L vs. 146 ± 62 10⁹/L and the mean highest calcium level was higher 11.3 ± 2.5 vs. 10.6 ± 0.8 mg/ dL in infants with SFN vs. infants without SFN, respectively (P-values of 0.0078 and 0.006, respectively). Distribution of skin lesions followed distinctive patterns representing the areas with direct contact with the cooling blanket. One infant developed severe, life-threatening hypercalcemia that required aggressive management, including diuretics, corticosteroids and bisphosphonates. Conclusion: Although SFN is a rare complication of therapeutic hypothermia, it can be a life-threatening condition if complicated by severe hypercalcemia. Infants who undergo therapeutic hypothermia for HIE need regular skin examinations to evaluate for SFN. If SFN is identified, monitoring of serum calcium levels to prevent life-threatening hypercalcemia is recommended.