A case of fulminant cryofibrinogenemia with rapid renal dysfunction and toe necrosis

Abstract Background There are few reports of kidney disease caused by cryofibrinogen (CF). There are still many unknowns regarding its diagnosis, treatment, and prognosis. Case presentation A woman in her 70s experienced gross hematuria without any triggers; no urinary abnormalities had been previously detected. At the same time, the urine protein level was 5 g; therefore, a renal biopsy was performed. Light microscopy revealed a membranoproliferative glomerulonephritis-like pattern. And the electron microscopic findings were extremely characteristic and specific. Development of ischemic lesions was observed in the lower legs. A skin biopsy performed at the sites of toe necrosis showed fibrinoid necrotizing vasculitis and thrombi in the blood vessels. Eventually, the patient was diagnosed with cryofibrinogenemia (CF-emia) by mass spectrometry. The effect of steroids was limited. Subsequently, the patient’s renal function rapidly deteriorated, and toe necrosis progressed. The patient died after initiation of hemodialysis. Conclusion Although CF-emia is an unknown disease and has been infrequently reported, no reported cases exhibited rapid worsening of toe necrosis and renal function during the same period. Therefore, this case can be said to be the first case of fulminant cryofibrinogenemia. Due to the development of nephropathy, which is likely to be a factor for poor prognosis, establishment of therapeutic strategies is urgently required.