Interstitial pneumonia and nodular regenerative hyperplasia of the liver as initial manifestations of polyarteritis nodosa

A 65-year-old man was admitted to our hospital because of progressive dyspnea. A laboratory examination and high-resolution computed tomography (HRCT) revealed that he had interstitial pneumonia (IP) with liver dysfunction. Myeloperoxidase-ANCA (MPO-ANCA) was negative. Although his respiratory condition had become stable after initiation of steroid therapy, liver dysfunction had worsened with progressive portal hypertension. He died of hepatic insufficiency about three years after the first medical examination. Autopsy showed that he had vasculitis of medium and small blood vessels of the spleen, lungs, and liver. The final diagnosis was classical polyarteritis nodosa (PAN). Microscopically, non-specific interstitial pneumonia was identified in the autopsied lung. The pathological findings of the liver were consistent with nodular regenerative hyperplasia (NRH). We report a case of PAN with IP and NRH preceding findings of systemic vasculitis.