Appendiceal orifice submucosal tumor: neuromuscular and vascular hamartoma

A 61-year-old man was admitted to the gastroenterology department with a history of abdominal discomfort. He denied any past illness and family history of malignant tumors. Laboratory, electrocardiogram, and physical examination showed no obvious abnormality. Later, the patient underwent the colonoscopy, and a 1.0*1.0 cm submucosal tumor (SMT) was presented at the appendiceal orifice. Endoscopic ultrasound showed that the SMT was a well-distributed hyperechoic lesion. Endoscopic submucosal dissection (ESD) was performed, and the SMT was resected in a whole piece. Post-ESD histopathological examination showed a well-differentiated mass, which comprised bundles of nerve fibers, fascicles of smooth muscle, and vascular channels. Further immunohistochemistry revealed mass cells that stained positive for S-100, CD34, and SMA. Histopathological examination and immunohistochemistry demonstrated a neuromuscular and vascular hamartoma (NMVH).