ESPE Abstracts

Background: Subcutaneous fat necrosis of the Newborn (SCFN) is a rare disease occurring in the first days of life. Characteristically the infants show hard nodules in subcutaneous tissue, purple or erythematous in color and appear on the upper back, cheeks, buttocks and limbs. In most cases SCFN is a self-limiting disease, as the nodules disappear in up to 6 months. A severe complication associated with SCFN is hypercalcemia. Pathophysiological mechanisms causing SCFN or associated hypercalcemia are not fully understood yet.

Objective: We aimed to identify risk factors for SCFN or associated hypercalcemia and to better understand pathophysiologic mechanisms.

Methods: A systematic literature research following the PRISMA-Statement including the six biggest databases for medical research has been used to identify all published case reports of SCFN. N=206 publications has been identified containing n=320 case reports. All cases have been classified into four subgroups (depending on the given serum-calcium-level): hypercalcemia, normocalcemia, hypocalcemia or no information given. Reported maternal factors, birth characteristics, details about SCFN, diagnostics, therapy and long-term observations have been extracted from publications.

Results: This is the first systematic literature research that summed up all published cases of SCFN from 1948 up to 2018. Information about serum calcium level was given in 64.3% of the cases. From those, the majority showed hypercalcemia (70.5 %) (normocalcemia: 25.1%, hypocalcemia: 4.3%). 89.3% of newborns with hypercalcemia showed suppressed levels of the parathormone. We identified, that maternal gestational diabetes, maternal hypertensive diseases during pregnancy, macrosomia (>4000g), asphyxia and therapeutic hypothermia are risk factors for SCFN. Histological findings showed a granulomatous inflammation in 98% of cases.

Discussion: We identified that maternal, birth characteristics and therapeutic measures are probably risk factors for SCFN. These risk factors should be taken into account by the practically active paediatricians. Hypoxic cell damage is thought to be the cause of subcutaneous fat necrosis in patients with SCFN. The majority of patients with SCFN develop hypercalcemia. It is assumed that granulomatouse inflammation in patients with SCFN is causing a lack of the negative feedback mechanism of the enzyme 1-α hydroxylase. As a result of this missing negative feedback mechanism vitamin D is overproduced. This causes an increased absorption of calcium via the intestine and consequently hypercalcemia. Hypercalcemia seems to be independent from parathormone levels in affected newborns.