Polyarteritis nodosa presenting with TAFRO signs following COVID-19 infection: case report.

The diagnostic criteria for TAFRO syndrome exclude autoimmune diseases, and they have been considered to be mutually independent. However, several cases of autoimmune diseases with TAFRO signs have been reported in recent years. Also, similarities in cytokine profiles in COVID-19 and TAFRO syndrome have been previously reported. Our patient, a 53-year-old Japanese man, was diagnosed with COVID-19 and had a persistent fever. Two weeks later, pain, numbness, and oedema appeared, mainly in the right lower leg but gradually spreading to the distal extremities. Subsequently, purpura appeared on his forearms and lower legs, and 10 weeks after the COVID-19 diagnosis he presented to our hospital. On admission, in addition to fever, polyangiitis, and purpura of the extremities, he had splenomegaly, lymphadenopathy, and anasarca. Skin and renal histopathology revealed fibrinoid necrotising vasculitis of small and medium-sized arteries. In addition, his platelet count was low, Alkaline phosphatase (ALP) was elevated, and there was anasarca, fever, and renal failure. A diagnosis of polyarteritis nodosa with TAFRO signs was made. On the 20th day of admission, high-dose glucocorticoids and high-dose intravenous cyclophosphamide were started. The platelet count initially improved, with gradual improvement of vasculitis and symptoms of fever, purpura, and neuropathy. However, there was another decrease in platelets, progression of renal dysfunction, and worsening of fluid retention. Tocilizumab was added, but the disease could not be controlled, and on the 51st day, necrotising fasciitis developed and the patient died. This case suggests that COVID-19, TAFRO syndrome, and vasculitis may be interrelated in their pathogeneses.