Polyarteritis nodosa limited to calf muscles: a case report and review of the literature.

We describe an unusual case of a 38-year-old woman with a localised form of polyarteritis nodosa (PAN) manifested by acute onset of severe calf pain. Magnetic resonance imaging of the lower legs showed abnormal signal intensity of the outer calves muscle. Biopsies of the gastrocnemius revealed an acute necrotising arteritis with marked non-specific fasciitis. The diseased muscle improved with corticosteroid administration alone. The fascial involvement likely contributed to the severity of the clinical features of PAN, which may be related to a previous hepatitis B virus infection.