Purulent appendicular peritonitis revealing an appendiceal mucocele: a case report.

INTRODUCTION: Appendiceal mucoceles are rare entities, often discovered incidentally or presenting with chronic, nonspecific abdominal symptoms. Acute purulent peritonitis, as an initial presentation, is exceptionally uncommon. Recognizing this atypical presentation is essential, as it may reveal an underlying appendiceal mucinous neoplasm with important therapeutic and prognostic implications. CASE PRESENTATION: We report the case of a 26-year-old man with a 1-year history of intermittent abdominal pain and diarrhea who presented with an acute abdomen. Laboratory investigations showed elevated inflammatory markers. Abdominal CT scan revealed a dilated appendix with mural calcifications and associated intraperitoneal purulent fluid. Emergency laparotomy demonstrated generalized purulent peritonitis and a perforated, distended appendix with a distal cystic mass. An appendectomy was performed. Histopathological examination confirmed a ruptured low-grade appendiceal mucinous neoplasm without evidence of invasive carcinoma or malignant peritoneal cells. CONCLUSION: Purulent appendiceal peritonitis may rarely be the initial manifestation of an underlying mucinous neoplasm. This case highlights the importance of considering this diagnosis in atypical presentations of the acute abdomen and underscores the role of histopathological assessment and multidisciplinary management in guiding optimal treatment and follow-up.