Atypical hemolytic uremic syndrome (HUS) is extremely rare in adults. HUS is characterized by hallmark features of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury. Atypical HUS (aHUS) is caused by uncontrolled complement activation. The complement activation can be triggered by infections such as Streptococcus pneumoniae or influenza, pregnancy, malignancy, cytotoxic drugs, organ transplants, or autoimmune diseases. Genetic mutations and autoantibodies have been found to play a crucial role in the pathogenesis of dysregulated complement activity. The majority of cases of atypical HUS due to invasive S. pneumoniae infection are more commonly seen in children. We present a case of S. pneumoniae HUS (Sp-HUS) presenting with multiorgan failure, disseminated intravascular coagulation (DIC), and limb ischemia in an adult. This case highlights the importance of considering S. pneumoniae HUS (Sp-HUS) in the differential diagnosis of thrombotic microangiopathies (TMA) in adults.

Calciphylaxis, or calcific uremic arteriolopathy, is a rare but particularly morbid condition involving systemic medial calcification of arterioles causing ischemia and subsequent tissue necrosis. Although most commonly occurring over the abdomen and proximal extremities, calciphylaxis can present on nearly any skin surface with a tendency toward areas of increased adiposity. We report a case of a 53-year-old female with end-stage renal disease who presented with bilateral palpable breast masses and overlying skin changes. Diagnostic mammography and percutaneous biopsy of the lesion facilitated the diagnosis of calciphylaxis and she was treated with medical therapy, local wound care, and eventual tissue extirpation. Due to the morbidity attributed to calciphylaxis and associated wound complications, surgical extirpation is at times unavoidable. Once malignancy has been excluded, we recommend nonoperative management with prompt referral to Nephrology for medical optimization, reserving surgical debridement for nonhealing wounds and superinfection.