[Renal ultrasound in fat necrosis]. / Intérêt de l'échographie rénale dans la cytostéatonécrose sous-cutanée.

Subcutaneous fat necrosis is an uncommon disease that may be complicated with potentially fatal hypercalcemia or with nephrocalcinosis. We report on the case of a patient with a history of significant perinatal asphyxia, hospitalized for a urinary tract infection. Lesions of subcutaneous fat necrosis were noted, with asymptomatic hypercalcemia at 3.9mmol/L. A renal ultrasound was performed and showed echogenic medullary pyramids bilaterally, consistent with nephrocalcinosis and left nephrolithiasis. The treatment of hypercalcemia included hyperhydration, a diuretic and corticosteroids. Progression was characterized by the total regression of skin lesions and normalization of serum calcium. Hypercalcemia is a rare complication of subcutaneous fat necrosis. It develops within days to weeks after the appearance of skin lesions. Nephrocalcinosis appears after several weeks or months. Hypercalcemia must be treated in due time to avoid the impact on the kidney.