Bladder invasion by appendiceal cancer is rare, accounting for only a small proportion of all gastrointestinal tumors. The common presenting symptoms of appendiceal cancer include appendicitis, abdominal pain, bloating, altered bowel habits, and, in severe cases, ileus. Here, we present a case of appendiceal cancer in a patient who presented with recurrent urinary tract infections over a six-month period.

A 45-year-old female with no significant medical history presented with turbid urine and dysuria persisting for six months. Urinalysis revealed pyuria and hematuria, leading to a presumptive diagnosis of a urinary tract infection, for which antibiotics were administered. However, her symptoms recurred frequently. Further evaluation with bladder sonography revealed a heterogeneous mass protruding into the urinary bladder. Abdominal computed tomography (CT) demonstrated a 5-cm hypoenhancing mass in the distal ileal region with enterovesical fistula formation. Colonoscopy identified an ulcerative tumor approximately 5 cm in size at the ileocecal valve. A biopsy revealed adenocarcinoma with focal signet-ring cell differentiation. The patient subsequently underwent laparoscopic right hemicolectomy and partial cystectomy. Final pathology confirmed poorly differentiated adenocarcinoma with transmural invasion into the urinary bladder, along with two tumor deposits in the subserosa, resulting in a pathological stage of pT4bN1cM0. Postoperatively, she received concurrent chemotherapy with oxaliplatin and fluorouracil (mFOLFOX) along with radiotherapy targeting the tumor bed near the urinary bladder.

Primary malignancies of the appendix are rare, constituting less than 1% of all gastrointestinal tumors. The most common presentation of appendiceal cancer is appendicitis, and malignancy is rarely suspected before surgery. Appendiceal cancer with bladder invasion has only been described in isolated case reports, in which tumors directly invade the bladder and form fistulas. Due to the anatomical proximity of the appendix to the bladder, patients with bladder invasion may develop urinary symptoms such as dysuria and recurrent infections before manifesting gastrointestinal symptoms. Histologically, approximately 80% of appendiceal tumors are neuroendocrine in origin, whereas only 20% are adenocarcinomas. For appendiceal adenocarcinomas, current guidelines recommend right hemicolectomy with adequate lymphadenectomy, and adjuvant chemotherapy should be considered for high-risk stage II and stage III disease. In cases where the tumor invades the bladder, prognosis is relatively favorable if the tumor remains resectable.

Recurrent urinary tract infections warrant further evaluation through imaging or cystoscopy to identify potential underlying causes. We present a rare case of appendiceal adenocarcinoma with bladder invasion, where the patient exhibited only recurrent urinary tract infections without any gastrointestinal symptoms. This case highlights an uncommon cause of recurrent urinary tract infections that merits further investigation.