<num>. chronic right pleural thickening. <num>. slight worsening of reticular pattern in right mid and lower lung region. review of prior pet-ct from <unk> demonstrates diffuse septal thickening in the right lung, which likely corresponds to this radiographic pattern. the etiology is uncertain but could potentially be due to lymphoma. drug-induced lung disease is more typically bilateral. an acute infectious process superimposed on chronic interstitial abnormalities is an additional consideration, and followup radiographs may be helpful in this regard if warranted clinically.