Severe neonatal hypercalcemia caused by subcutaneous fat necrosis without any apparent cutaneous lesion

Subcutaneous fat necrosis is a classic, albeit uncommon, cause of neonatal hypercalcemia. It occurs in newborn infants within the first month of life following a complicated delivery. The diagnosis is usually easy because of the presence of red-purple plaques in fatty areas along with firm subcutaneous nodules. A 1-month-old neonate, born strangled by her umbilical cord, presented with diarrhea and hypercalcemia (3.46 mM) with an initial physical examination considered normal. Her biological evaluations were as follows: P = 1.37 mM (1.6–2.2); PTH = 3 ng/L (12–65); 25-OH vitamin D = 87 nM (23–113); (1,25)-OH₂ vitamin D = 192 ng/L (20–46). The third day, a careful exam of the whole cutaneous surface revealed small firm subcutaneous nodules in the ischial region. Despite the absence of any visible skin modification, the association of perinatal stress and high (1,25)-OH₂ vitamin D level with subcutaneous nodules led to the diagnosis of subcutaneous fat necrosis. She was treated with oral prednisone for 45 days. Serum calcium levels normalized within a week, and the nodules disappeared without complications. Conclusion: Subcutaneous fat necrosis may induce severe hypercalcemia without any visible cutaneous lesion.