Introduction
Purtscher’s retinopathy is a rare retinal disorder characterized by acute visual loss and retinal findings such as cotton-wool spots, intraretinal hemorrhages and retinal whitening following head or chest trauma.1 When the etiology is not a trauma, the disease is called Purtscher-like retinopathy. Numerous conditions such as acute pancreatitis, connective tissue disorders, autoimmune diseases, pregnancy-related diseases, and thrombotic microangiopathic diseases can cause Purtscher-like retinopathy.2
Atypical hemolytic uremic syndrome (aHUS) is a very rare life-threatening disease. It is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal failure.3 It is differentiated from hemolytic uremic syndrome (HUS) by the absence of diarrhea and Shiga toxin-induced infection.4 The main pathology of aHUS is dysregulation of the complement system, leading to vascular endothelial damage and complement aggregations.
Discussion
Purtscher-like retinopathy is a very rare retinal disorder with an incidence rate of 0.24 patients per million per year.1 The most encountered signs of this retinopathy are cotton-wool spots, retinal hemorrhages, Purtscher flecken, pseudo-cherry red spot, and macular edema, respectively.2 The generally accepted pathophysiology of Purtscher-like retinopathy is vascular endothelial damage and arteriolar precapillary occlusion by emboli of leucocytes, fibrin, fat, and complement aggregates. This retinopathy is mostly seen with acute pancreatitis, renal failure, autoimmune diseases, and thrombotic microangiopathies such as TTP, HUS, and DIC.
aHUS is a thrombotic microangiopathy caused by mutations of factor H, factor I, factor B, membrane cofactor protein, C3 convertase component, and thrombomodulin gene.4 These abnormalities lead to dysregulation of the complement alternative pathway, which causes thickening of arterioles and capillaries, endothelial detachment, subendothelial accumulation of proteins, cell debris, and fibrin-platelet thrombi obstruction.3 This pathogenesis of aHUS leads to systemic multi-organ involvement, and there are only a few reports showing the ocular involvement of aHUS in literature.5,6,7 Zheng et al.5 reported a case with recurrent ocular involvement which was consistent with central retinal vein occlusion/venous stasis retinopathy in the first attack, and inferior rectus paralysis in the second attack and was treated with steroids. Larakeb et al.6 reported a case of vitreous bleeding due to aHUS, and their patient improved with plasma exchange therapy after four weeks. David et al.7 described a patient with aHUS and serous retinal detachment who was treated with hemodialysis, plasmapheresis, and eculizumab. That case shares many similarities with our patient: same age, female sex, similar ocular findings, and successful response to eculizumab treatment. However, their patient had a lesser extent of retinal yellow-white patches compared to our patient. To the best of our knowledge, our patient is the first reported case of Purtscher-like retinopathy associated with aHUS.
Purtscher-like retinopathy is a very rare retinal disorder which is commonly caused by thrombotic microangiopathic diseases such as HUS and aHUS. These diseases are severe, life-threatening diseases and mostly occur in childhood or early adulthood. Therefore, performing a detailed fundus examination in every patient, especially in the pediatric age group, is crucial for recognizing these retinopathies which are caused by underlying life-threatening diseases.
