A New Finding in Psoriatic Nephropathy

Introduction: Minimal change disease (MCD) is a common cause of nephrotic syndrome that is notoriously responsive to steroids. However, atypical pathologic features or steroid resistance may suggest a secondary cause. Rare cases of the contested diagnosis Psoriatic Nephropathy have shown IgA nephropathy, amyloidosis, and drug-induced lesions on biopsy, but only 1 case to our knowledge has shown MCD. We present a case of steroid resistant MCD with the rare finding of mesangial proliferation in a patient with active psoriasis which may help to elucidate the mechanism of psoriasis induced kidney injury. Case Description: A 59-year-old male with active, untreated psoriasis but no other medical issues presented to the emergency department with headache and was found to have severe hypertension. Workup revealed 3.6g proteinuria, hypoalbuminemia, and anasarca. Nephrology was consulted for Nephrotic Syndrome. A kidney biopsy with 33 glomeruli showed marked foot process effacement without segmental sclerosis, most consistent with MCD. However, it also showed mild mesangial hypercellularity and mesangial matrix expansion without any immune complex deposition, as would be seen in IgA nephropathy, Lupus nephritis, or MPGN. Serologic work up and hemoglobin A1c were unrevealing. He started prednisone 1mg/kg daily for 1 month, but at follow up, he had 4g of proteinuria. Treatment was extended for another month, and his psoriasis and anasarca slightly improved, but he had unchanged proteinuria. He was started on tacrolimus, which can treat psoriasis as well; its efficacy is unclear at this time. Discussion: Psoriasis’ effect on the kidney has been difficult to pinpoint given the limited number of cases reported, but this case of MCD in a patient with active psoriasis flare is unique in that it is not confounded by other diagnoses or medications. Most proposed psoriatic nephropathy cases show mesangial proliferation due to IgA nephropathy, but our case would add to the 3 cases that show mesangial proliferation without IgA deposition. The mesangial proliferation in this biopsy that otherwise only shows MCD adds to the confidence that his MCD was triggered by psoriasis and is the first case to our knowledge to show this unique combination. Clinically, this is important as mesangial proliferation in MCD has been associated with initial steroid resistance as seen in this case and may need additional therapies to resolve the disease.