Rare growth pattern of a solitary cystic lung metastasis from colon cancer: a case report

An 82‐year‐old male, who had undergone sigmoid colon cancer surgery (at the age of 78 years) and primary lung cancer surgery (at the age of 81 years), was found to have a cavitating lesion in the left lower lobe on chest computed tomography (CT). A chest CT that had been performed just before the primary lung cancer surgery revealed a small thin‐walled cyst at the same site at which the cavity was detected in the current CT. Bronchoscopic examination revealed no evidence of malignancy. A follow‐up chest CT performed 5 months later revealed that the lesion had grown and that the cyst contained a well‐defined lobular nodule. Video‐assisted thoracoscopic left basal segmentectomy was performed. The histopathological diagnosis was metastasis from colon cancer. We report this unusual case in which a pulmonary metastasis changed over time from a cystic lesion to a nodular lesion.