Primary signet ring cell carcinoma of the appendix presenting as gangrenous appendicitis with peritonitis: a case report.

Introduction and clinical importance: Primary signet ring cell carcinoma (SRCC) of the appendix is an exceedingly rare malignancy with a non-specific clinical manifestations, and it often masquerades as acute appendicitis. Case presentation A 76-year-old man presented with acute abdominal pain and peritonitis. Abdominal computed tomography revealed relative acute appendicitis with peritonitis, and emergency laparoscopic partial cecectomy with appendectomy revealed gangrenous appendicitis with perforation. A histopathological examination revealed a primary appendiceal signet ring cell carcinoma (PASRCC). Clinical discussion: This case highlights the importance of considering appendiceal malignancies in the differential diagnosis of acute appendicitis. SRCC is a histological variant commonly associated with multiple malignancies of the gastrointestinal tract, particularly gastric and colorectal cancers. Conclusion: PASRCC is a rare malignancy presenting with symptoms indistinguishable from those of acute appendicitis. Clinicians should maintain a high index of suspicion for appendiceal malignancy, particularly in older patients with atypical clinical presentations. Early recognition, accurate diagnosis by histopathological and immunohistochemical examinations, and appropriate management are essential for optimizing the outcomes in these patients.