Appendiceal mucocele (AM) or Appendiceal mucinous neoplasms is a rare but potentially dangerous condition. In the latter, a spontaneous or iatrogenic rupture of the mucocele can lead to mucinous intraperitoneal ascites, a syndrome known as pseudomyxoma peritonei. We present the case of a 76-year-old female patient who reported right iliac fossa pain with RIF tenderness on clinical examination, and underwent an abdominal CT scan showing an appendiceal mucocele associated with a small peritoneal effusion suspecting a ruptured mucocele, related to peritoneal pseudomyxoma. The patient underwent appendectomy with peritoneal lavage and aspiration of all mucin found. Anatomopathological analysis confirmed the diagnosis of appendiceal mucocele (a low-grade appendiceal mucinous neoplasm).