A case of colorectal cancer with urinary tract infection induced by bayberry pits

Colorectal cancer is a common tumor of the digestive system and is the third leading cause of cancer-related death worldwide. The global incidence of colorectal cancer is currently increasing. In some patients, the tumor has already spread to nearby organs at the time of diagnosis, with the small intestine and bladder being common sites of invasion.^[1,2] The diagnosis of colorectal cancer that has spread to the bladder can be challenging. Aside from a few patients who experience urinary symptoms due to invasion of the bladder trigone or the entire bladder wall, there are no distinct clinical signs, which often leads to misdiagnosis. The following case report details one such instance.

The patient was an 80-year-old male without significant medical history. In January 2024, he began to experience changes in bowel movements, with unformed and yellow stools 3-4 times per day. He attempted to self-medicate with various folk remedies, such as bayberry wine, but his symptoms did not improve significantly. On June 25, 2024, he began to experience urinary tract irritation, including frequent, urgent, and painful urination. On June 28, 2024, he visited the gastroenterology clinic for evaluation. Laboratory tests revealed a white blood cell count of 11.2×10⁹/L, a neutrophil count of 8.6×10⁹/L, a high-sensitivity C-reactive protein (hs-CRP) level of 101.4 mg/L, and abnormal stool results (1-2 red blood cells/HP, 10-15 white blood cells/HP, occult blood positive). Urinalysis revealed no white blood cells or bacteria. The diagnosis of “enteritis” was considered, and the patient was treated with anti-infective agents and intestinal flora regulation. However, after two days of treatment, the patient reported no improvement and discontinued the treatment on his own.

By July 14, 2024, the patient experienced worsening diarrhea, increased bowel movements, and loose and watery stools. Abdominal pain also intensified after eating, but it was relieved by defecation. On July 18, he returned to the gastroenterology clinic for follow-up. Physical examination revealed no obvious abdominal muscle tension, mild tenderness throughout the abdomen, and no rebound pain, but percussion pain was noted in both kidneys. The laboratory results showed a white blood cell count of 15.8×10⁹/L, a neutrophil count of 14.0×10⁹/L, and hs-CRP level of 145.8 mg/L. Symptomatic treatment, including antidiarrheals, was provided, and the patient was advised to consult a nephrologist.

Upon visiting the nephrology clinic, further tests revealed a routine urine test with red blood cells (409/μL), white blood cells (7,039/μL), and bacteria (269/μL). A diagnosis of urinary tract infection and enteritis was suggested. On July 19, the patient was admitted to the nephrology department for inpatient care. During his stay, the patient developed paroxysmal abdominal pain and ceased passing gas or stool. Colonoscopy revealed a purple-red mass 18 cm from the anal margin that was cauliflower shaped with surface erosion and necrosis, suggestive of colon malignancy. Abdominal and pelvic computed tomography (CT) scans revealed gas accumulation in the bladder, thickening of the intestinal wall, and sinus formation. On August 5, 2024, the patient underwent radical resection of the colon. During surgery, it was found that the tumor had invaded the serosa of the bladder (Figure 1). After extensive dissection, more than 40 bayberry pits were removed (Figure 2), and the following pathology confirmed a diagnosis of moderately differentiated adenocarcinoma. Postoperatively, the patient was transferred to the intensive care unit (ICU) for continued care. The endotracheal tube was removed on August 6, and he was transferred to the gastrointestinal surgery department on August 8. He started a liquid diet on August 9 and was discharged on August 13, 2024.

Figure 1. The colon tumor invaded the serosa of the bladder.

Figure 2. Bayberry pits located in the serosal muscle layer of the colon and bladder.

Colorectal cancer is one of the most common malignancies, with high morbidity and mortality rates. The typical clinical symptoms include blood in the stool, abdominal pain, and changes in bowel habits.^[1,3,4] As the disease progresses, colorectal cancer can spread locally or metastasize distantly. Local spread can involve adjacent organs such as the liver, small intestine, and bladder, leading to the formation of various types of fistulas.^[3] When colorectal cancer invades the bladder, it can lead to the formation of enterovesical fistulas (EVFs), which typically present with urinary symptoms, including urinary tract irritation, pneumaturia, and recurrent infections.^[5]

EVFs are abnormal connections between the intestine and the bladder. Depending on the part of the intestine involved, they can be classified into four types: colonic (most commonly between the sigmoid colon and bladder dome), rectal, ileal, and appendiceal fistulas.^[6] While EVFs are rare, they are most often caused by diverticulitis, malignancies (particularly colorectal cancer), or Crohn’s disease.^[6] Gouverneur syndrome, characterized by suprapubic pain, frequent urination, dysuria, and tenesmus, is commonly associated with EVFs.^[7] The diagnosis is confirmed primarily through auxiliary imaging methods such as cystoscopy, CT, and magnetic resonance imaging (MRI), with clinical symptoms providing additional support. Surgical treatment remains the primary approach for managing these conditions.^[6,8]

In this case, the patient initially presented with gastrointestinal symptoms. However, owing to tumor invasion of the bladder serosa, combined with the patient’s use of bayberry wine and ingestion of bayberry seeds, the seeds likely migrated to the colon and bladder wall. This led to urinary tract irritation and recurrent infections. When patients present with both gastrointestinal and urinary symptoms, the possibility of an EVF secondary to intestinal malignancy should be considered. Diagnostic tests such as colonoscopy, ultrasound, and CT imaging can be helpful. The patient was eventually transferred to the Gastrointestinal Surgery Department for radical colon resection, where it was found that the tumor had invaded the bladder serosa and that more than 40 bayberry seeds had embedded within the colon and bladder wall. Pathology confirmed moderately differentiated adenocarcinoma. The patient underwent comprehensive postoperative care and was discharged after recovery.

In conclusion, bladder invasion caused by colorectal cancer is difficult to diagnose clinically and is often misdiagnosed. This condition should be considered in patients with persistent gastrointestinal symptoms accompanied by urinary tract symptoms. Colorectal bladder fistulas are rare and are caused primarily by direct tumor infiltration into adjacent organs. Diagnosis requires a combination of clinical findings, imaging studies, endoscopy, and pathological evidence. Surgical treatment is the mainstay for patients in good general condition with disabling symptoms.

Funding: The study was supported by the Project of National Natural Science Foundation (82372206), the Project of Jiangsu Provincial Health Commission (H2023107), and the Project of Basic and Clinical Research on Cardiac Arrest in the Emergency and Critical Care Department of the Second Affiliated Hospital of Soochow University (XKTJ-XK202408-2).

Ethical approval: Not needed.

Conflicts of interest: None.

Contributors: SMY and HRL contributed equally and are co-first authors. All authors contributed to the design and interpretation of the study and to further drafts.