直腸NET G1の転移例

Neuroendocrine Carcinoma Classified as G1（NET G1）with Synchronous and Metachronous Metastases, Report of a Case

要旨●患者は60歳代，男性．内視鏡検査にて，下部直腸に中心陥凹を伴う粘膜下腫瘍を認め，腫瘍径13mm，深達度cT1と診断された．骨盤MRIで約10mmの側方リンパ節腫大を疑い，リンパ節郭清を伴う超低位前方切除術が施行された．術後診断はNET G1，pT1，深部リンパ管および静脈侵襲陽性，傍側方リンパ節1か所で陽性であった．18か月後のFDG-PETで肺に集積を認め，肺CTと気管支鏡下吸引細胞診の結果，両側肺転移と診断された．転帰は，緩和療法下のみで3年経過中である．NET G1の遠隔転移は稀少であるが，初回診断時の腫瘍径や深達度，同時性転移などの病期が関与するところが大きいと考えられる．

　A 65-year-old male presented with a submucosal tumor with central depression in his lower rectum. Initial endoscopic findings revealed that the tumor was 13mm in diameter, and its clinical depth was classified as T1. The patient underwent very low anterior resection with radiological resection of lymph nodes ; therefore, the neuroendocrine tumor was reclassified as G1（NET G1）, pT1, N1, M0, stage III. After 18 months, FDG-PET revealed FDG accumulation in the lungs, and multiple lung metastases were diagnosed by bronchoscope guided（fine-needle aspiration extology）fine-needle aspiration cytology. The patient was observed for three years under supportive care.“Hot spots”under Ki-67/MIB-1 staining helped in the assessment and total surgical removal of NET G1. Such a case of NET G1 with metachronous metastasis is rare and would not have been predicted at the initial stage on the basis of the size and depth of the tumor and synchronous metastasis.