Hypercalcemia in neonatal subcutaneous fat necrosis: A systematic review of risk factors, timing, and complications.

BackgroundSubcutaneous fat necrosis (SCFN) of the newborn is a rare panniculitis. It is characterized by erythematous, indurated nodules or plaques involving the back, buttocks, or extremities. Although the lesions usually resolve spontaneously, SCFN can be complicated by hypercalcemia. This complication may lead to significant morbidity and mortality. This review summarizes the risk factors, timing, and complications of hypercalcemia in SCFN.MethodThis review followed the PRISMA 2020 statement (Registration ID: CRD420251145895). A systematic search was conducted in PubMed, Scopus, ScienceDirect, EBSCO, and ProQuest for studies published between 2015 and 2025. Case reports, case series, observational studies, and reviews reporting SCFN with calcium data were included. Data on risk factors, timing of onset, and complications were synthesized narratively.ResultsThirty-one studies were included. The most common reported maternal risk factors were gestational diabetes mellitus (GDM) (7/30) and hypertension or preeclampsia (5/30). Perinatal hypoxia, especially asphyxia (30/35), was the predominant neonatal factor. SCFN lesions typically appeared within the first 3 weeks of life (wks of life), while hypercalcemia developed within 8 wks of life. Nephrocalcinosis (NC) was the most common complication (18/28).ConclusionSCFN is a systemic condition with a substantial risk of delayed or persistent hypercalcemia. This review highlights the delayed onset of hypercalcemia, which may occur weeks after skin lesion development. These findings emphasize the need for extended monitoring, including serial calcium assessment and renal imaging, to prevent overlooked complications and improve neonatal outcomes.