囊胞性病変を呈した浸潤性粘液性腺癌の1例

Invasive Mucinous Adenocarcinoma that Invades the Wall of a Cystic Lesion：Report of a Case

はじめに　浸潤性粘液性腺癌（IMA）は，肺癌取扱い規約（第8版）より新たに導入された概念で，従来は粘液性細気管支肺胞上皮癌（BAC）に分類されていたものである．肺腺癌特殊型に分類され，比較的まれな組織型である．孤立・多発結節影や浸潤影などの画像所見を呈することが多いが，囊胞性病変を呈したIMAを経験したので報告する．

Invasive mucinous adenocarcinoma （IMA） is a rare and special type of lung adenocarcinoma. We report a case of IMA presenting as a cystic lesion in the S10 of the right lung, diagnosed by surgical biopsy and treated with right lower lobectomy. The patient was a 60-year-old man who was found to have a 10-mm-sized frosted ground-glass opacity with a 10-mm-sized air space in the S10 of the right lung while undergoing follow-up after renal cancer surgery in 2018. The air space gradually enlarged and, in 2022, began to show a 40-mm-sized cyst, with partial wall thickening and nodularity on the caudal side. A thoracoscopic partial pneumonectomy was performed to confirm the diagnosis of IMA, and a thoracoscopic radical resection of the right remaining lower lobe was performed. It is important to recognize that adenocarcinoma may occur in patients with thin-wall cavity, as in this case. Additionally, it is necessary to determine the treatment strategy based on the assumption that the tumor may extend to the entire cavity wall, even if it is thin-walled.