Figure 7a. Methotrexate-induced NSIP in a 41-year-old woman with rheumatoid arthritis who presented with dyspnea and decreased diffusing capacity of the lungs for carbon monoxide (DLCO). (a) High-resolution CT scan shows scattered ground-glass attenuation and thickened inter- and intralobular lines (arrow). (b) Photomicrograph (original magnification, x400; hematoxylin-eosin stain) of a specimen from lung biopsy shows patchy interstitial fibrosis, expansion of the interstitium by chronic inflammatory infiltrates, and reactive hyperplastic type II pneumonocytes (arrow), findings consistent with NSIP induced by the pulmonary toxic effects of methotrexate.