Abstract
Appendiceal mucinous adenocarcinoma is a term that was given for invasive appendiceal tumors. It is always present with pseudomyxoma peritonei which is a complex disease. These tumors have the tendency to surround the primary tumor then extend primarily and extensively all over the peritoneal cavity as the primary site of metastases. The invasion through the abdominal wall muscles is rare but the penetration and passing through these muscles to the subcutaneous tissue are extremely rare. A 62-year-old male patient known to have pseudomyxoma peritonei presented with gluteal abscess. After 2 weeks from the abscess drainage, the patient underwent cytoreductive surgery (CRS) combined with intraoperative radiotherapy (IORT) and hyperthermic intraperitoneal chemotherapy (HIPEC). He tolerated the operation well and discharged home in a good condition. Even with extensive appendiceal mucinous neoplasms presented with the penetration of the abdominal wall muscles, still aggressive management should be considered.