Renal papillary necrosis in patients with sickle cell disease: How to recognize this 'forgotten' diagnosis.

INTRODUCTION: Renal papillary necrosis is not commonly seen in daily practice, but can have severe consequences when it is not diagnosed in time. It is known to be associated with sickle cell hemoglobinopathies; however a wide range of etiologies are possible, and it is therefore not the first diagnosis clinicians consider in patients with sickle cell disease who present with hematuria. METHODS: A literature search was performed to summarize the current knowledge about renal papillary necrosis associated with sickle cell disease. These findings are illustrated with a case of a 9-year old girl with sickle cell disease who was referred with painless gross hematuria. RESULTS: Typical radiologic signs for renal papillary necrosis are necrotic cavities that fill with contrast, small collections of contrast peripheral to the calyces in the papillary region (ball-on-tee sign), calcification of the papillary defect, filling defects, hydronephrosis, blunted papillary tip, clefts in the renal medulla filled with contrast, hyperattenuated medullary calcifications, non-enhanced lesions surrounded by rings of excreted contrast, and clubbed calyces. DISCUSSION: This study focuses on the pathophysiology of renal papillary necrosis associated with sickle cell disease, the possible symptoms, as well as the diagnostic steps, with a special interest in particular presentation on old (retrograde pyelography) and new (computed tomography) gold standard in radiologic imaging, and the management for this pathology. CONCLUSION: This study aims to remind clinicians of this "forgotten" diagnosis and what signs to look for in pediatric patients with sickle cell disease who present with hematuria. In pediatric cases radiation protection is important, therefore knowing what radiologic signs can be found on retrograde pyelography can lead to early identification of this pathology without having to proceed to computed tomography.