AC is a primary esophageal motor disorder, and the esophageal motility testing is the gold standard for the diagnosis of AC, but some studies have pointed out that its role in identifying pseudoachalasia is limited [4, 5]. There are many causes of pseudoachalasia including benign and malignant diseases, and the proportion of pseudocardiac achalasia caused by malignant tumors exceeds 50% [6, 7]. Most of them can be diagnosed through upper gastrointestinal angiography, multiple gastroscopy and biopsy, chest CT and other auxiliary examinations to find malignant signs to confirm the diagnosis; but for those patients with early lesions and negative auxiliary examinations, the diagnosis is often difficult. In this case, no malignant signs were found on the endoscope and upper gastrointestinal angiography before POEM, and the thickening of the cardia on the lesser curvature side reported by chest CT was not obvious, which can be explained by contracture of the cardia sphincter [8]. During the POEM operation, it was found that the mucosa was tightly adhered to the muscularis, which was not consistent with the intraoperative performance of conventional AC patients. A mucosal bleb was easily created by submucosal injection in general AC patients and the endoscope can be easily introduced into the submucosal area[9]. This is because AC, as a benign lesion, does not damage the anatomical structure of each layer of the esophagus wall, so that the mucosal layer and the muscular layer can be separated smoothly. Combined with the pathological results, we analyzed that the adhesion of the tissue was caused by the infiltration and growth of the malignant tumor under the mucosa and the destruction of the surrounding tissue structure, resulting in the scar of the surrounding tissue. At this time, if the diagnosis of pseudoachalasia is considered, the prognosis may be better after effective treatment after pathological results are obtained. Of course, the positive rate of pathological examination of specimens obtained under endoscopy is not 100%, but the signs in this POEM operation can give us a good reminder of possible malignant diseases. In addition, endoscopic ultrasound plays an important role in the differential diagnosis of two diseases. The American College of Gastroenterology recommends that esophageal ultrasound endoscopy (EUS) be performed on patients with suspected pseudoachalasia, which can further find some invasive tumors. Some studies have pointed out that EUS can find smaller diameters submucosal cancer that any other examination can’t found out[2, 10].
POEM is a new method for treating AC in recent years. Due to its good safety and effectiveness, it is more and more commonly used in the treatment of AC [11]. There have been report of patient with esophageal leiomyoma who have been definitely diagnosed and treat when performing POEM[12]. However, it’s rarely reported that cases of pseudoachalasia caused by malignant tumors accidentally discovered by POEM. Especially for cases where there is no obvious positive test result in the preoperative auxiliary examination, if serious adhesion between the mucosa and the muscularis is found during POEM, it is particularly important to remind clinicians a diagnosis idea: Adhesion might be caused by malignant diseases.