Stage IA2 lung adenocarcinoma followed by benign necrotizing sarcoid granulomatosis mimicking recurrence

What happened, in summary

This 63-year-old man had undergone video-assisted thoracoscopic right lower-lobe posterior basal segmentectomy in July 2022 for lung adenocarcinoma staged pT1bN0M0, Stage IA2. He was followed with regular chest CT scans. On August 10, 2023, CT showed a 12 × 6 mm solid nodule in the right middle lobe and several solid subpleural nodules in the right upper lobe and at the surgical site. These nodules gradually enlarged over time. A CT performed shortly before admission in March 2025 showed the right middle-lobe lesion had grown to 16 × 13 mm, with additional enlarging nodules in the right upper lobe and surgical field. Because of his lung cancer history, metastatic disease or recurrence was a concern. Bone ECT showed no bone metastasis, and fungal and tuberculosis tests were negative. PET-CT showed FDG uptake in the right middle-lobe nodule, supporting the concern for malignancy. After multidisciplinary discussion, he underwent VATS biopsy and removal of nodules from the right upper lobe, right middle lobe, and visceral pleura. Frozen sections showed coagulative necrosis and granulomatous inflammation. Final pathology confirmed necrotizing sarcoid granulomatosis rather than cancer recurrence, with acid-fast and PAS stains negative. Because the enlarged nodules had been removed and laboratory tests were otherwise unremarkable, his physician recommended continued observation without glucocorticoid therapy. He had no cough, sputum, dyspnea, fever, night sweats, or fatigue, and the physical exam was unremarkable aside from the prior surgical scar. Inflammatory markers, blood counts, procalcitonin, ESR, and CRP were within normal limits. The right lung findings were still categorized as Lung-RADS 4A, so tissue diagnosis was needed before assuming recurrence.