Mistaken identity: an unexpected case of spontaneous cholecystocutaneous fistula formation

Abstract

We describe the case of a 78-year-old woman who presented to the emergency department with a 2-week history of a superficially developing mass in the lower right abdominal wall, fluctuant and non-tender with overlaying erythematous skin changes. Though resembling an abdominal wall abscess and initially listed for a simple incision and drainage, diagnostic uncertainty encouraged further investigation. CT and ultrasound confirmed the mass appeared to be in continuity with the gallbladder fossa, with the lumen also containing small bowel medially. While awaiting a multidisciplinary team discussion, the patient re-presented with concern over discharge appearing at the site of the mass. On inspection, we noted black flecks and small stones. This case describes the unusual and rare presentation of a cholecystocutaneous fistula. The patient was managed conservatively and remains clinically well.

Background

The manifestation of abdominal wall masses is commonplace in acute surgical admissions. Imaging may be necessary to delineate underlying pathology in aiding diagnostic certainty. We present the unusual case of a gallbladder herniation through a previous ileostomy site, with eventual fistulisation and expulsion of multiple gallstones.

Case presentation

A 78-year-old woman presented to the emergency department with a 14-day history of a non-resolving right-sided abdominal mass. As a relatively fit and well patient, she had endured an extensive surgical history. In 2009, she presented critically unwell with septicaemia secondary to multiple intra-abdominal abscesses and underwent an emergency hemicolectomy with ileostomy formation. In the years following this, she underwent an ileostomy reversal complicated by anastomotic breakdown and later anastomotic bleed. Further complications were encountered as she developed multiple enterocutaneous fistula formations requiring surgical management and thus, contended with complicated wound management. Our patient had in total undergone eight laparotomies over the past decade though had been largely free of abdominal ailments for the past 5 years. Her medical background also included previous renal calculi requiring ureteric stenting and multiple right-sided inguinal hernia repairs. She was not on any regular medication.

On examination, the patient was thin and mobilised independently. There was a 2×3 cm mass palpable in the right lower quadrant of her abdomen, subtly fluctuant with associated erythematous skin changes. It was non-tender, non-reducible and cough impulse was negative. She gave a history of fever and gradual weight loss in the preceding 6 months and mentioned her bowel motions were slightly looser than normal. She denied any pain, nausea or vomiting. Observations were unremarkable, with a heart rate of 80 beats/min and temperature of 36.8°C.

Investigations

Clinically, the patient was quite well with a normal white blood cell count and only mildly raised Creactive protein of 12 mg/L. All other bloods were unremarkable on presentation. Initially, no further investigations were thought necessary; however, on return to our theatre receiving unit the following morning in anticipation of a simple incision and drainage, re-examination prompted concern about the possibility of other underlying intra-abdominal pathology.

A CT scan carried out in the past month at the request of her general practitioner was re-examined and discussed with our radiology team (figure 1). A concern arose that the cystic collection in the right lower quadrant may have a fistulous connection with the gallbladder fossa. Multiple densities seen within the collection, originally thought to be contrast, appeared consistent with gallstones (figure 2). We requested an ultrasound scan which reaffirmed this suspicion, that the gallbladder had herniated through a previous ileostomy site and lay intimately related to a loop of small bowel.

Figure 1.

Coronal view of CT abdomen and pelvis showing herniation of the gallbladder lumen and part of small bowel into the right-sided abdominal wall.

Figure 2.

Transverse view of CT abdomen and pelvis showing herniation of the gallbladder lumen and part of small bowel into the right-sided abdominal wall. Multiple densities within the herniation represent gallstones.

Differential diagnosis

Differentials in this patient initially included abdominal wall abscess due to the fluctuant nature of the mass palpated on examination. However biochemically, inflammatory markers were normal, and the mass was non-tender. This created diagnostic suspicion, and with a background of multiple surgeries, herniation of bowel seemed a possible diagnosis also. Malignancy should be considered with any palpable mass, however, was unlikely given the short history in which the mass had presented itself.

Treatment options

A minimally invasive approach is particularly important in this case as our patient has a significant surgical history, having undergone multiple laparotomies over the past decade.

The complex nature of this herniation and accompanying skin changes posed the question of what preventative measure should be taken to avoid future complications in this patient. We decided on a multidisciplinary team meeting to explore potential management options.

Trans-papillary drainage of the gallbladder with cystic duct stenting via endoscopic retrograde cholangiopancreatography (ERCP) is a useful and well-established short-term measure in facilitating biliary drainage.¹ However, it can be a technically challenging procedure as deep biliary cannulation is required to approach the gallbladder and requires complete understanding of the origin of the cystic duct take-off and pattern. Post-ERCP pancreatitis remains a significant complication of this procedure.^{1 2}

Endoscopic ultrasound (EUS)–guided gallbladder drainage is an effective non-invasive method that has yielded fewer post-procedure complications than alternative drainage methods. Typically carried out via the use of therapeutic linear array echoendoscope, a trans-gastric or trans-duodenal to gallbladder puncture can be made with a 19-gauge needle. Once bile is aspirated, a guide wire is introduced to secure position. The puncture site is then dilated, and a stent of choice is introduced into the gallbladder. Plastic stents, self-expanding stents and the more recent lumen-apposing metal stent (LAMS) have been used in this approach.^{2 3}

LAMS are advantageous as they can be placed in a single step using an EUS scope only. They also provide better tissue apposition at both ends, reducing the risk of stent migration and risk of leakage around the stent as seen in plastic stents.⁴ The wide inner diameter of LAMS also reduces the risk of stenosis and obstruction. In mimicking the natural drainage of biliary secretions into the duodenum, LAMS may be left in situ indefinitely and has been associated with less reported patient discomfort.⁴

Outcome and follow-up

While awaiting further discussions, the patient re-presented to the emergency department. Though clinically well, the right-sided lump had begun spontaneously discharging yellow viscous fluid with specks of black solid matter approximately 0.5–10 mm in size. Photographs taken with the permission of our patient (figures 3 and 4) show the appearance of gallstones discharging from the mass in the right lower quadrant of the abdomen. The overlying skin had been intact 1 week prior to these photographs being taken.

Figure 3.

Removal of a stoma bag over the right lower quadrant revealed multiple specks of heterogeneous solid matter resembling stones.

Figure 4.

On closer inspection, we can see the formation of a fistula.

The appearance suggests the formation of a fistula from the lumen of the gallbladder to the surface of the abdominal wall, a rare cholecystocutaneous fistula.

Discussion

Cholecystocutaneous fistulas are an increasingly uncommon occurrence, with less than 30 cases reported in the literature in the past 50 years.^5–7 Historically, biliary fistulas were associated with long-standing inflammation of the gallbladder, giving rise to perforation and drainage of bile into the peritoneal cavity.⁶ In 1890, Courvoisier described a series of cases involving 499 patients who presented with gallbladder perforations; 169 were believed to have developed cholecystocutaneous fistulas.^8–10 In other cases, in literature, such fistulas are most often the result of iatrogenic complications post-percutaneous cholecystostomy.^{9 10} With the advent of elective laparoscopic cholecystectomies and anti-microbials in the management of cholecystitis, external and internal biliary fistulas are far less common these days.

In this case, we present the herniation of the gallbladder lumen into the right lower quadrant of the abdominal wall, which has likely resulted from an unprecedented number of laparotomies that have left this patient’s abdominal musculature deficient and vulnerable to herniation. Fistulisation occurs as a result of adherence of the gallbladder to the abdominal wall.

This case highlights the necessity of having a high index of suspicion when encountering a patient with a complex surgical history. As in this case, accurate diagnosis of this entity avoids unnecessary morbidity. As such, CT is a reliable imaging modality in identifying and diagnosing intra-abdominal fistulas.¹¹ However, as per literature, ultrasound sonography is considered more specific and sensitive in the diagnosis of gallbladder pathology.¹¹

Management of cholecystocutaneous fistulas depends largely on the balance of risk factors. Previous studies have shown that in patients with an unobstructed biliary system, such fistulas spontaneously resolve.^{12 13} However, definitive cholecystectomy with incision of the fistulous tract may be considered.^{12 13}

Patient’s perspective.

Our patient reflected on this experience as “a trying chapter in my life”. In regards to the outcome, they commented, “I am happy that there is no need for surgery right now and hope for this to resolve on its own accord.”

Learning points.

• Considering background surgical history is important when examining abdominal wall abnormalities.

• Consider varying differentials even if diagnosis appears typical.

• A conservative management approach may be acceptable when evaluating the risks and benefits of surgical intervention.

• The role of CT and ultrasound imaging is pivotal in removing diagnostic uncertainty when identifying intra-abdominal pathology.