Gallbladder cancer has produced an exceptionally rare and unsettling complication in a 65-year-old man: a spontaneous tunnel from the diseased organ to the skin, allowing a gallstone to emerge through the abdominal wall. The case, described by clinicians as a spontaneous cholecystocutaneous fistula, illustrates how an apparently benign bile-duct narrowing can conceal an aggressive, infiltrative cancer until the disease has spread beyond the limits of curative surgery. It also highlights a diagnostic trap: gallbladder tumors do not always form an obvious mass, and conventional scans and blood tests can appear reassuring even as malignancy advances.
Gallbladder carcinoma is uncommon, but it is among the most aggressive cancers of the biliary tract. Many patients have few specific symptoms during its early stages, and the disease is often discovered only after it has invaded nearby organs, obstructed the bile ducts, or metastasized. Surgery is generally the only treatment with curative potential. Once the tumor involves the hepatic pedicle, major bile ducts, stomach, colon or distant organs, however, an operation may no longer be technically feasible. For unresectable disease, treatment becomes palliative, aiming to relieve obstruction, slow tumor growth and preserve quality of life. Median survival is frequently less than a year in advanced cases.
The patient first sought medical attention in November 2022 with gradually worsening abdominal pain, jaundice, itching, weight loss and a general decline in health. He had no fever and no notable previous medical history. Contrast-enhanced computed tomography showed a swollen gallbladder containing multiple stones. Its wall was mildly and regularly thickened, but radiologists could not identify a distinct mass. Imaging also showed enlargement of the intrahepatic bile ducts upstream from an approximately 18-millimeter narrowing involving the common hepatic duct and the upper common bile duct. The stricture appeared short, smooth and regular, without obvious invasion of the liver, enlarged regional lymph nodes or peritoneal spread.
Magnetic resonance cholangiopancreatography supported the impression of a relatively orderly, tapered obstruction rather than an overtly malignant lesion. There was no irregular “shouldering,” an intraductal mass or conspicuous mural abnormality. Tumor markers, including carcinoembryonic antigen and carbohydrate antigen 19-9, were within normal limits. Yet these markers are imperfect: normal levels do not reliably exclude gallbladder cancer or other biliary tumors. Endoscopic ultrasound and dedicated hepatobiliary ultrasound were not performed at the initial evaluation. In retrospect, that omission may have mattered, because these techniques can provide higher-resolution views of the gallbladder wall and the tissues surrounding the bile ducts, where subtle infiltrative cancers may hide.
The case was therefore initially managed as a likely benign biliary stricture. During endoscopic retrograde cholangiopancreatography, doctors observed regular narrowing and normal-appearing duct lining, with no filling defects. The gallbladder did not fill with contrast. A plastic stent was inserted to drain the bile, and brush cytology from the narrowed duct was negative for malignant cells. The patient was scheduled for elective gallbladder removal. But when surgeons began laparoscopically, the anatomy looked very different from the scans. The gallbladder was distended and had an unusually thick wall. It was tightly fused to the gastric antrum and the hepatic flexure of the colon, making safe dissection difficult.
The operation was converted to an open procedure through a right subcostal incision. Surgeons found a hard, stone-like mass involving the common bile duct, the hepatic pedicle, the lower stomach and the right side of the colon. A separate whitish lesion, about two centimeters wide, was visible in segment III of the liver. The pattern indicated locally advanced gallbladder carcinoma with extension into the extrahepatic bile ducts, and the disease was judged unresectable. Rather than risk a dangerous and incomplete operation, the team abandoned resection and biopsied the liver lesion. Pathological examination identified a well-differentiated adenocarcinoma compatible with biliary origin and confirmed that the liver contained a metastasis.
The patient subsequently received a metal biliary stent and 12 cycles of GEMOX, a chemotherapy combination of gemcitabine and oxaliplatin used for advanced biliary tract cancers. During the early treatment cycles, imaging suggested stable disease, although formal RECIST response criteria were not applied. His condition was monitored every two to three months through clinical examinations, liver-function tests and contrast-enhanced CT scans. Molecular testing for potentially actionable alterations, such as changes involving HER2, FGFR2, IDH1 or NTRK, was not performed because next-generation sequencing was not readily accessible. Treatment consequently followed established chemotherapy practice rather than a genomically selected strategy.
In September 2023, several months after the diagnosis and during the course of systemic therapy, the patient developed a soft, inflamed swelling measuring about five centimeters at the right subcostal surgical scar. He had no laboratory evidence of systemic inflammation, and his kidney, liver and coagulation tests remained normal. CT imaging revealed a thick-walled gallbladder filled with stones and positioned directly against the right rectus abdominis muscle. The muscle appeared heterogeneous and infiltrated. Between the gallbladder and the skin was a subcutaneous collection containing a calcified focus measuring approximately 32 by 21 millimeters. The finding suggested an abscess caused by a developing cholecystocutaneous fistula, with a gallstone migrating into the abdominal wall.
Surgeons drained the swelling and recovered blood-tinged fluid as well as a gallstone, providing direct evidence that the gallbladder had eroded toward the skin. Such fistulas are much more commonly associated with neglected gallstones or chronic cholecystitis than with cancer. In this patient, the process was probably driven by several forces acting together. Tumor infiltration can compromise blood vessels in the gallbladder wall, causing ischemia and tissue death. Chronic inflammation and obstruction can raise pressure inside the organ, while stones repeatedly scrape and irritate the lining. The combination can produce microscopic perforations, infection and gradual extension into neighboring tissues. As the gallbladder was already adherent to the abdominal wall, the path of least resistance led outward, eventually creating a channel through muscle and subcutaneous tissue.
A review accompanying the case found fewer than 10 well-documented reports of cholecystocutaneous fistula caused by gallbladder carcinoma. Most patients were older adults with advanced adenocarcinoma, local invasion, gallstones and poor prospects for surgery. In several cases, the fistula was already present when the cancer was diagnosed. The current patient appears unusual because the fistula formed after the initial operation and during palliative chemotherapy rather than being the presenting feature. Still, the complication should be interpreted as a sign of advanced disease, not necessarily as a direct toxic effect of chemotherapy. The tumor’s contact with the abdominal wall, combined with necrosis and chronic inflammation, likely created the conditions for the fistula.
The report underscores why a smooth bile-duct stricture should not automatically be considered harmless when it occurs alongside gallstones, jaundice and unexplained weight loss. CT and magnetic resonance imaging remain essential for staging, but their sensitivity can fall when tumors grow as diffuse infiltrations rather than discrete masses. High-resolution ultrasound and endoscopic ultrasound can sometimes reveal irregular thickening of the gallbladder wall, invasion around the ducts or suspicious lymph nodes that are less apparent on routine scans. Repeated imaging, tissue sampling when feasible and close multidisciplinary review may be warranted when symptoms and imaging do not align. Once fistulization occurs in an unresectable tumor, care focuses on drainage, infection control, pain relief, nutritional support and maintaining biliary drainage, with chemotherapy offered when the patient can tolerate it. The authors emphasize that earlier recognition of infiltrative gallbladder cancer may offer the best chance of preventing this dramatic complication.
