腹腔内出血にて発見され腹腔鏡下に摘出したPDGFRA遺伝子変異を伴う大網GISTの1例

Laparoscopic resection for PDGFRA-mutant gastrointestinal stromal tumor in the greater omentum presenting with intraabdominal hemorrhage : a case report

◆要旨：患者は72歳女性，腹痛を主訴に来院した．CTにて腹腔内に血性腹水と腫瘤様陰影を認めた．血管造影で大網血管を塞栓したが，緩徐に貧血が進行した．再検したCTで腫瘤は移動しており．大網腫瘍からの出血を疑い，腹腔鏡下手術を行って長径13cmの腫瘍を摘出した．病理組織検査で類上皮細胞が増殖し，免疫染色ではKIT（-），CD34（＋）であり，血小板由来増殖因子レセプターα（PDGFRA）遺伝子に変異を認め，大網gastrointestinal stromal tumor（GIST）と診断した．術後5年間無再発である．腹腔内出血を伴った巨大なGISTに対しても腹腔鏡下手術は低侵襲で有用な治療法と思われた．

　A 72-year-old woman consulted our hospital with abdominal pain. Computed tomography（CT） scan showed an intra-abdominal mass and extravasation of contrast medium from the omental artery. Abdominal angiography was performed and peripheral branch of the omental artery was embolized with coils. However, follow-up laboratory exam revealed further anemia, suggesting continuous bleeding. CT showed intra-abdominal mass moving toward the right upper quadrant ; thus, we hypothesized bleeding from an omental tumor. We performed laparoscopic resection of the tumor, which turned out to be an omental GIST. The tumor showed diffuse epithelioid cells, positive for CD34 but negative for KIT. Subsequent investigation revealed PDGFRA mutations. So far, there is no recurrences. PDGFRA-mutant GIST is likely to grow large but has low malignant potential. Laparoscopic surgery is a useful and minimally invasive procedure for such GIST even with intra-abdominal hemorrhage.