Adenocarcinoma with mediastinal lymph node involvement developed from a pure ground grass nodule during 14 years

A 69‐year‐old female Japanese patient presented with an abnormal shadow on chest computed tomography (CT). She had received a mastectomy 14 years prior. Under the diagnosis of primary lung cancer, left upper lobectomy was conducted. Pathology showed a lepidic adenocarcinoma with mediastinal lymph node metastases with pT2aN2M0. Upon retrospective analysis, the chest CT at the time of mastectomy depicted a ground‐glass nodule (GGN) of less than 20 mm. Over the previous 10.5 years, the concentration of the central part of the GGN increased. Conclusively, a pure GGN developed into lung adenocarcinoma with mediastinal lymph node involvement over 14 years. She had bone metastases 4 years after the lobectomy but has survived for five and a half years after surgery with treatment with osimertinib. Comparison readings of films should be performed throughout the patient's clinical history to detect subtle shadow alterations indicative of tumour progression.