伊藤 将倫¹, 竹田 欽一², 鵜飼 宏司², 荒川 大吾², 岩嶋 佳子², 森下 哲司², 秦野 貴充¹, 須網 芳弘¹, 今泉 延¹, 小栗 健二¹

Masatsugu ITO¹, Kinichi TAKEDA², Hiroshi UKAI², Daigo ARAKAWA², Yoshiko IWASHIMA², Tetsuji MORISHITA², Takamitsu HATANO¹, Yoshihiro SUAMI¹, Tadashi IMAIZUMI¹, Kenji OGURI¹

¹偕行会名古屋共立病院画像技術課, ²偕行会名古屋共立病院消化器内科

¹Department of Image Technology, Nagoya Kyoritsu Hospital, ²Department of Gastroenterology, Nagoya Kyoritsu Hospital

キーワード : endoscopic ultrasound, pancreas, serous cystadenoma, solid-variant type, ultrasound

肉眼的に充実性腫瘍の形態を示した膵漿液性嚢胞腺腫(solid-variant type)の1例を経験したので報告する. 症例は51歳, 女性. 主訴は心窩部痛. 腹部超音波検査(US)にて膵体部に充実性腫瘍を指摘され, 精査加療目的にて入院となった. 入院時USでは, 膵体部に約2 cm大の境界明瞭, 低エコーの充実性腫瘍を認め, 内部に線状の高エコーを認めた. PFDモードにより腫瘍の辺縁より拍動性の血流シグナルが得られた. 超音波内視鏡検査(12 MHz画像)では, 腫瘍はほぼ円形で被膜の存在をしめす側方陰影を有し, 内部均一な高エコー像として描出された. 一方, 周波数7.5 MHzでは, 腫瘍辺縁の輝度は下がり, 正常膵実質と同程度に変化した. 造影CTおよび腹部血管造影検査では, 著しく豊富な血流を有する充実性腫瘍であった. 膵内分泌腫瘍を疑い, 膵体尾部脾合併切除術を施行した. 割面肉眼所見は2×1.5 cm大の被膜で覆われた充実性腫瘍であった. 病理学的には, 腫瘍は多数の小嚢胞から構成され, 間質には毛細血管が豊富に認められた. 本症例は, 肉眼的に充実性腫瘍像を呈したが, 病理組織診断では, 極めて小さい嚢胞の集簇した膵漿液性嚢胞腺腫(solid-variant type)であり, 膵内分泌腫瘍との鑑別が困難であった. なおUS, EUSでエコー輝度が異なるという特徴的な所見を呈していた.

We treated a case of serous cystadenoma of the pancreas that grossly exhibited the morphology of a solid tumor of the solidvariant type. The patient was a woman aged 51 years whose chief complaint was epigastric pain. Abdominal ultrasonographic examination detected a solid tumor in the body of the pancreas, and the patient was admitted to the hospital for thorough examination and treatment. Ultrasound examination at time of admission showed a solid, hypoechoic tumor with a diameter of about 2 cm. Pulsatile flow detection (PFD) mode ultrasound showed that the tumor had clear boundaries, was located in the body of the pancreas, and contained internal hyperechoic streaks. PFD mode also detected pulsating blood-flow signals at the margin of the tumor. Endoscopic ultrasound examination (12-MHz EUS) showed an almost perfectly spherical tumor containing a lateral shadow and evidence of a capsule and visualized it as an internally homogeneous hyperechoic lesion. When the tumor was examined using 7.5-MHz EUS, however, the brightness of its margin decreased to that of normal pancreatic parenchyma. Contrast CT and abdominal angiography revealed a solid tumor with highly abundant blood flow. A pancreatic endocrine tumor was considered, and combined resection of the pancreatic body and tail was carried out. Gross inspection of the cut surface of the surgical specimen revealed an encapsulated solid tumor that measured about 2×1.5 cm. Pathologically, the tumor was composed of numerous small cysts, and capillaries were clearly visible in the stroma. The lesion exhibited the gross characteristics of a solid tumor. The diagnosis of a solid-variant type serous cystadenoma of the pancreas formed by clusters of extremely small cysts was first based on histopathologic findings. The lesion was difficult to differentiate from a pancreatic endocrine tumor. Echogenecity in ultrasound and endoscopic ultrasound differed, and the tumor yielded remarkable findings.