Falciform ligament appendagitis after Roux-en-Y bypass surgery mimicking acute cholecystitis

Background

The incidence of fatty falciform ligament appendage torsion (F-FLAT) is extremely rare, with only 10 cases being reported on imaging in the literature to date.1–9 There are a handful of cases identified by surgical exploration without imaging, mostly before 1980.10–14 Like other intraperitoneal focal fat infarctions (IFFIs), falciform ligament appendagitis is caused by torsion of an abnormally long lipomatous appendage leading to ischemia, infarction and ultimately aseptic fat necrosis. The presentation is variable but classically involves acute or subacute epigastric pain that does not radiate, with a low-grade fever and mild leukocytosis. The major risk factor for IFFI is obesity, specifically, increased abdominal visceral adipose tissue, which is more common in men.15 For unknown reasons, obese individuals tend to have longer, more prominent appendages that are presumably more prone to torsion.16 Given the rising rates of obesity and bariatric surgery, it is becoming increasingly important to identify this medical oddity.

Case presentation

A 46-year-old obese woman with a history of laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery for obesity 10 months prior, presented to the emergency department with 3 days of worsening right-upper-quadrant (RUQ) pain described as ‘stabbing‘' that was exacerbated by meals, and 8/10 in severity. On physical examination she demonstrated exquisite tenderness to palpation in the right upper quadrant and epigastric regions, with guarding but no rebound tenderness. Basic laboratory tests revealed elevated liver enzymes with aspartate aminotransferase (AST) of 56 units/L (normal: 5–34 units/L), alanine aminotransferase (ALT) of 63 units/L (normal: 10–55 units/L), alkaline phosphatase of 164 units/L (normal: 40–150 units/L), and neutrophilia (absolute neutrophil count 5.63×10³ neutrophils/µL).

Investigations

Out of concern for acute cholecystitis, a right upper quadrant ultrasound was performed and it was negative for the classical signs of acute cholecystitis (gallbladder wall thickening, common bile duct dilatation, etc) but did show a small polyp and a 3 mm hyperechoic stone in the gallbladder neck, with the twinkle artefact (figure 1). A sonographic Murphy’s sign was equivocal due to the patient’s exquisite tenderness to even mild palpation. A CT was then performed that demonstrated an 18.8×9.6 mm ovoid focus of fatty necrosis on the falciform ligament consistent with a torsed fatty appendage of the falciform ligament (figure 2). On this finding, a hepatobiliary iminodiacetic acid scan that had been scheduled was cancelled.

Differential diagnosis

The presentation of F-FLAT is highly variable and can present as acute abdominal pain with or without fever, anorexia, nausea, vomiting or radiation to the back.3 As such, it can mimic surgical or post-surgical complications such as marginal ulcers or cholecystitis17 or nonsurgical conditions such as gastritis, hepatitis or pancreatitis.

Our patient had exquisite right upper quadrant abdominal pain that was exacerbated by meals, radiated to the back and neutrophilia, making the presentation highly suspicious for acute cholecystitis. Her weight, gender, age and premenopausal status are also known risk factors for acute cholecystitis. Moreover, cholecystitis is a common occurrence after LRYGB surgery, with 10.6% of patients ultimately requiring cholecystectomy.17 The incidence of symptomatic gallstones is highest in the first 6 months after LRYGB surgery, and the mean time to cholecystectomy is 19.1 months after surgery.17 Ultimately, a right-upper-quadrant ultrasound and abdominal CT did not demonstrate evidence of cholecystitis (figure 1), and the diagnosis of F-FLAT was made.

The perigastric pain of F-FLAT can also mimic other acute surgical conditions such as a perforated gastric or marginal ulcer. This was especially concerning as our patient had a recent Roux-en-Y surgery, the most common complication of which is ulcer formation near the anastomosis (marginal ulcer) that occurs in up to 16% of patients, and can potentially perforate.18 Our patient underwent endoscopy as part of the diagnostic workup that did not demonstrate marginal ulcers as the cause of her pain.

Anastomotic dehiscence was also on the differential. To our knowledge this is the first case of F-FLAT in a patient with a prior LRYGB surgery. Her stable hemodynamics, lack of systemic symptoms such as fever, absence of imaging findings of perforation on CT, and relatively benign bloodwork suggested against dehiscence as the aetiology of her pain.

F-FLAT with prandial pain, such as in our patient, can also mimic nonsurgical conditions such as biliary colic, gastritis, hepatitis or pancreatitis. Although she had elevated liver enzymes, the relatively modest increase in AST, ALT and alkaline phosphatase, as well as absence of systemic symptoms such as fever, was less consistent with hepatitis. Additionally, her hepatitis A, B and C serologies were negative for infection. To our knowledge, there has been only one other case of F-FLAT that presented with elevated liver enzymes and hepatitis.9

Treatment

Unlike the surgical conditions it mimics, F-FLAT should be managed conservatively, as most cases resolved completely within 3–14 days.1 2 19 Treatment is typically with non-steroidal anti-inflammatory medications (NSAIDs), and surgery is warranted only in cases where symptoms fail to resolve with conservative therapy, or a rare complication develops, such as inability to tolerate oral intake, abscess or gangrenous necrosis.5 In our patient, NSAIDs were avoided due to the risk of marginal ulcer formation, a common complication of LRYGB surgery, and she was instead given acetaminophen and oxycodone for pain relief with good effect.

Outcome and follow-up

Two weeks after the initial presentation, the patient reported resolution of her pain, and a repeat CT demonstrated significant interval reduction in the size of the F-FLAT (figure 3).