Mucus-filled lesion of a distal viable remnant tip of an appendix that developed 23 years after appendectomy

INTRODUCTION: Post-appendectomy mucus-filled lesions, arising from appendiceal remnant tissue, are an exclusively rare clinical entity. We report a rare case of a mucus-filled lesion rising from a distal viable remnant appendiceal tip as a late complication of appendectomy. PRESENTATION OF CASE: A 48-year-old man presented with a 2-week history of right buttock and right lower quadrant abdominal pain. He had previously undergone appendectomy 23 years ago. Radiological examination showed a cystic lesion lateral to the colon with a prominent tubular structure. According to the past operative note, the appendiceal tip was lost accidentally. Surgical resection was performed. Pathologic examination revealed a mucus-filled lesion lateral to the cecum, with no communication between them. There was no evidence of malignancy. The prominent structure had muscular layer, suggestive of distal appendiceal remnant. DISCUSSION: Surgical resection of appendiceal mucus-filled lesion is recommended, because there are no reliable criteria to exclude malignant lesions. Although appendiceal mucus-filled lesion is rare, it is extremely rare in patients with previous appendectomy. In our case, the mucinous material secreted from the remnant appendix might be enclosed by the surrounding tissue. CONCLUSION: In patient with previous appendectomy who show a cystic mass close to the cecum, the possibility of lesion derived from the appendiceal stump or distal appendiceal remnant should be considered. In such cases, it is important to review the medical records for a definitive diagnosis. Complete appendectomy, without leaving appendiceal tissue, remains mandatory to prevent the development of late complications of mucus-filled lesions.