BackgroundCholesterol embolization syndrome (CES) is an increasingly recognized cause of acute renal insufficiency, which must be differentiated from other forms of systemic vasculitis by histologic examination of biopsies from involved organs. This report describes the optimal methods for detection and biopsy of areas of skin involved with livedo reticularis to confirm the diagnosis of CES.MethodsThis report describes 8 patients with unexplained acute renal insufficiency in whom the diagnosis of CES was suspected based on their clinical history.ResultsA detailed skin examination performed in both supine and upright postures demonstrated the presence of previously unrecognized livedo reticularis, which was more evident during upright posture in all subjects. In 2 subjects, questionable areas of livedo reticularis noted in supine posture became readily demonstrable during upright posture. Livedo reticularis was apparent only during upright posture in 2 subjects. Biopsies of areas of skin involved with livedo reticularis demonstrated cholesterol emboli in 6 of 8 patients and were normal in the remaining 2 patients. One patient progressed to end-stage renal disease and one was lost to follow-up. In the remaining 6 patients, renal insufficiency initially progressed but did not require dialytic therapy. Renal function returned to baseline levels and livedo reticularis resolved without recurrence in these patients. No subjects developed clinical or laboratory evidence of systemic vasculitis.ConclusionsLivedo reticularis is a common but often unrecognized finding in CES that may not be evident during routine examination performed in the supine posture. Deep cutaneous biopsy of areas of livedo reticularis can be safely used to confirm the presence of cholesterol emboli, thus avoiding the increased morbidity of biopsy of either pregangrenous skin lesions or visceral organs. Many patients with CES regain renal function during long-term follow-up.