平滑筋腫に併存した早期食道癌の1例

Early Carcinoma of the Esophagus Coexisting with Esophageal Leiomyoma, Report of a Case and a Review of the Literature

要旨　患者は71歳，男性．胸やけを主訴として他院で胸部中上部（ImIu）の食道粘膜下腫瘍の診断を受けた．約5年半の経過観察の後，同部に表在癌が発見され，手術を目的として当科入院．胸部食道全摘+胸骨後経路頸部食道・胃管吻合を施行した．切除標本では，食道の平滑筋腫上からその口側にかけて表在陥凹型，深達度mmの早期食道癌が認められた．また，下部食道には逆流性食道炎の所見が存在した．食道における平滑筋腫に併存した早期癌は極めてまれで，本邦では本症例を含め6例が報告されている．これらの症例における癌腫の多くは，平滑筋腫の直上から口側にかけて存在しており，食物の停滞などによる機械的，化学的刺激による発癌の可能性が示唆された．

　A 71-year-old man complaining of heartburn was diagnosed by endoscopic biopsy as having esophageal cancer. This diagnosis followed a 5.5-year-follow-up of a submucosal tumor of the esophagus by another hospital. After examination, he was admitted to our department for surgery.

　Esophagography showed a round protruded lesion having a slightly rough mucosal surface (Fig. 1). Endoscopic findings indicated a round protruded lesion with a reddish rough mucosal surface unstained by Lugol's solution (Fig. 2). Endoscopic ultrasonography outlined a low echoic lesion continuing through the muscularis propria (Fig. 3).

　Esophagectomy with reconstruction was performed. The resected specimen revealed superficial carcinoma (3.6×2.8 cm) coexisting with a submucosal tumor (3.0×2.1×1.5 cm) in the upper resected esophagus. Esophagitis was also confirmed in the lower part of it (Figs. 4 and 5). Microscopic findings showed moderately differentiated squamous cell carcinoma penetrating as far as the muscularis mucosae, without lymph node metastasis (Figs. 5 and 7). It also revealed leiomyoma which seemed to arise from the muscularis propria (Fig. 6). The patient was discharged with no post-operative complications, and has experieneced no recurrence seven months since.

　Early carcinoma of the esophagus coexisting with esophageal leiomyoma is rare, and only 6 cases, including the present case, have been reported to date in Japan (Table 1). In almost all of these cases, the carcinomas partially overlapped the oral side of the leiomyomas (Fig. 8). This suggests that cancer arises through the continuous physicochemical stimulus of food.