Extrahepatic manifestations are generally believed to be immune-mediated.
Polyarteritis Nodosa: rare, though serious. It affects small- and medium-sized vessels of multiple organ systems. Hepatic manifestations are usually mild.
Treatment is a combination of antiviral and immunosuppressive therapies, with plasma exchange.
HBV-associated glomerulonephritis (GN) : commonly in male children. It's usually self-limited , but may rarely progress to renal failure. In adults, the risk of progression to renal failure is higher.
Treatment: antiviral therapy.
Serum-sickness: in 30% of patients; with joint and skin symptoms.
Onset of clinical hepatitis is associated with resolution of these symptoms, although arthritis may persist in some patients.
Mixed essential cryoglobulinemia : purpura, arthralgias and weakness. It may be complicated by nephritis, pulmonary disease and generalized vasculitis.
Skin manifestations: palpable purpura.