Appendiceal Adenocarcinoma Presenting as a Pelvic Mass with Liver Metastasis: A Case Report

Abstract

Background: Appendiceal adenocarcinoma is a rare malignancy, accounting for less than 1% of all gastrointestinal neoplasms. Due to its nonspecific clinical presentation, diagnosis is frequently delayed and often occurs incidentally or at advanced stages. Metastatic disease may be present at the time of diagnosis, posing significant diagnostic and therapeutic challenges.

Case Report: A 36-year-old woman with no significant medical history presented with a 2-month history of right upper quadrant abdominal pain associated with diarrhea, nausea, vomiting, and an unintentional 9-kg weight loss. Laboratory evaluation revealed anemia, leukocytosis, thrombocytosis, hypoalbuminemia, elevated inflammatory markers, and abnormal liver function tests. Fecal occult blood testing was positive. Computed tomography demonstrated a 7 × 5 cm pelvic mass and a 3 cm hepatic lesion suspicious for metastatic disease. Image-guided liver biopsy revealed metastatic high-grade intestinal-type adenocarcinoma with extensive necrosis. Tumor marker analysis showed elevated CA 19-9 (1,200 U/mL) and CA-125 (38.4 U/mL). Following multidisciplinary evaluation, the patient underwent central venous catheter placement and initiation of neoadjuvant chemotherapy. Further diagnostic workup identified appendiceal adenocarcinoma as the primary tumor.

Conclusion: Appendiceal adenocarcinoma is an uncommon gastrointestinal malignancy that may present with vague abdominal symptoms and metastatic disease. This case highlights the importance of thorough diagnostic evaluation, including imaging and histopathological confirmation, in patients with unexplained abdominal symptoms and weight loss. Early multidisciplinary management is essential to optimize treatment planning and patient outcomes.