Subcutaneous fat necrosis of the newborn is a self-limited disorder of the panniculus that arises in the first six weeks of life. Some differential diagnoses may be difficult such as bacterial cellulitis or erysipelas. The prognosis is usually favorable but there are serious complications for which the patient must be regularly monitored, especially hypercalcemia. We report a case of a full-term newborn with a liquidated area of subcutaneous fat necrosis. A surgical incision was performed because of the discomfort and the lack of regression. Hypercalcemia and nephrocalcinosis appeared afterward. A set of clinical, biological, and histological arguments allows the diagnosis of subcutaneous fat necrosis. Follow-up to early detection and to manage such complications is necessary.