Question: A 44-year-old man presented with lower abdominal pain and diarrhea. He denied any respiratory symptoms. He had a 7-year history of ileocolonic CD. His medication included infliximab and azathioprine for 5 years, and mesalazine for 6 years. Loss of response to infliximab had been noted. Physical examination showed a body temperature of 37.2°C and left lower quadrant tenderness. Abdominal CT scan for bowel evaluation disclosed incidentally a nodule measuring 12 mm in diameter in the right lung (Fig. A, arrow). Sputum cultures and cytology showed negative results. Tests for tumor markers, β-D-glucan, the purified protein derivative, and in vitro interferon-γ release assay were also negative. Both bronchoscopy and CT-guided percutaneous biopsy failed to diagnose the lesion. As the nodule grew and primary lung cancer was not ruled out, the lung mass was resected by video-assisted thoracoscopic surgery for definite diagnosis. Gross examination revealed a solid yellow-white nodule measuring 25×20 ×13 mm (Fig. B). What is the most likely diagnosis?