Metastatic lobular breast cancer masquerading as achalasia.

Background and Aims: A 64-year-old woman with stage IV breast cancer taking exemestane presented with weight loss of 10 to 15 pounds and dysphagia of 3 to 6 months in duration. Upper endoscopy and positron emission tomography/computed tomography did not reveal a pathologic diagnosis. Esophageal manometry was suggestive of achalasia. The patient was referred for an esophageal peroral endoscopic myotomy (E-POEM) procedure. We aim to describe a rare finding encountered during submucosal dissection in an E-POEM that may result in an incomplete, aborted, technically challenging, or ineffective procedure. Methods: An E-POEM using a posterior approach is our preferred method. E-POEM was planned in the standard fashion. A mucosotomy followed by submucosal injection and dissection was performed, with plan for an extended circular and full-thickness myotomy of the lower esophageal sphincter. Results: During submucosal dissection, atypical yellow-brown tissue was encountered within the submucosal tunnel. This was initially thought to be related to fibrosis from severe achalasia. In total, 3 tunnels were created with eventual abortion of the procedure because this abnormal tissue was found 3 to 4 cm proximal to the esophagogastric junction in each tunnel. This tissue was biopsied, and all tunnels were closed without any postprocedural adverse event. Pathology demonstrated metastatic lobular breast cancer. Conclusions: Invasive lobular breast cancer has a propensity to spread to the GI tract as compared with other forms of cancer such as invasive ductal carcinoma. Endoscopists who perform E-POEM who encounter difficulty expanding the submucosal plane during E-POEM should keep malignancy and metastatic disease in mind as a rare cause of pseudoachalasia, even in the absence of nondiagnostic pre-peroral endoscopic myotomy evaluation.