Intravenous immunoglobulins in polyarteritis nodosa restricted to the limbs: case reports and review of the literature.

Polyarteritis nodosa (PAN) of the calf muscles is a rare form of vasculitis. We present two cases of PAN limited to the calf and a review of the literature, based on a MEDLINE (PubMed) search of the English literature from 1980 to 2005, using the key words "vasculitis restricted to limbs", "polyarteritis nodosa", and "intravenous immunoglobulin". PAN limited to the calf muscles is a condition presenting with severe shin pain and walking difficulties. In contrast to classic PAN, there is no skin, joint, visceral or nerve system involvement in this form of the disease. The main clinical signs are tenderness and swelling of the calf. Inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein, are usually elevated, and a perinuclear pattern of anti-neutrophil cytoplasm antibodies can be found. Electromyography of the calf is not contributory. Magnetic resonance imaging may be useful in recognizing the limb-restricted vasculopathy and selecting the muscle biopsy site, which is obligatory for diagnosis. Corticosteroids (CS) are the main treatment regimen, but CS-resistant cases have been reported. The patients presented here failed to respond to CS but were successfully treated with intravenous immunoglobulin therapy (IVIG). In the absence of vital organ involvement, the addition of cytotoxic drugs is controversial. IVIG seems to be an efficient alternative therapy in PAN limited to the calf muscles especially for patients with limitations to conventional cytotoxic treatment.