APPENDIX OR ASSASSIN? WHEN THE CECUM HIDES A KILLER horaciosousa98@gmail.com

PE088

APPENDIX OR ASSASSIN? WHEN THE CECUM HIDES A KILLER

7

Portugal

Poster Exhibition only

Neoplasms of the ileocecal appendix are rare, accounting for less than 1% of gastrointestinal tumors, and are often found incidentally. Mucinous adenocarcinoma stands out for its silent progression, with potential invasion of the serosa and dissemination into the peritoneum. Right hemicolectomy with clear margins is the standard treatment, complemented by adjuvant chemotherapy in advanced cases or in the presence of risk factors.

We report the case of a 55-year-old woman admitted for evaluation and pain control due to right iliac fossa pain and a palpable mass with a 2-month evolution. CT suggested a possible inflammatory appendicular process with upstream ureteral dilatation. MRI described a lesion in the appendix that could correspond to chronic appendicitis rather than a mucocele. It was decided to proceed with antibiotic therapy followed by elective surgery after resolution of the inflammatory process.

Following antibiotic treatment, an elective right hemicolectomy was performed without complications. Histology revealed a low-grade mucinous adenocarcinoma with serosal and perineural invasion, and lymph node metastasis (pT4aN1aR0). Postoperative colonoscopy showed no dysplasia. In multidisciplinary evaluation, HIPEC was not indicated, and adjuvant chemotherapy with CAPOX was initiated. The patient remains asymptomatic and under oncological follow-up.

This case highlights the importance of considering differential diagnoses in atypical presentations of appendicitis and the need for appropriate surgical intervention to confirm the diagnosis and define therapeutic management. The multidisciplinary approach was crucial in tailoring a personalized plan, with a good clinical response to date.