Sjögren's disease with mixed cryoglobulinemia presenting as a hypertensive emergency with thrombotic microangiopathy: a diagnostic puzzle.

We describe the case of a 50-year old woman presenting with hypertension-associated thrombotic microangiopathy (TMA) and nephrotic syndrome as an unusual initial presentation of a cryoglobulinemic glomerulonephritis secondary to primary Sjögren's disease. This case first highlights the importance of a thorough and systemic work-up in patients with TMA, given the broad differential diagnosis and diagnostic complexity. When initial evaluation does not reveal an underlying cause and TMA parameters improve with blood pressure control, a diagnosis of hypertension-associated TMA may be considered. However, hypertension-associated TMA is often secondary to an underlying auto-immune or primary renal disease, warranting further investigation. In this case, kidney biopsy revealed a membranoproliferative glomerulonephritis with hyaline thrombi. Electron microscopy showed subendothelial electron dense deposits, and serum analysis confirmed the presence of mixed cryoglobulins, establishing the diagnosis of cryoglobulinemic glomerulonephritis. Primary Sjögren's disease was suspected based on positive anti-Ro60 and anti-Ro52 antibodies and supported by the presence of sicca symptoms, and was finally confirmed by a positive Schirmer's test. This case illustrates the diagnostic value of a kidney biopsy in identifying the underlying etiology of TMA and it also highlights the importance of considering cryoglobulinemia in the differential diagnosis of membranoproliferative glomerulonephritis.