Mediastinal Pancreatic Pseudocyst-A Case Report and Review of the Literature

Abstract

Pancreatic pseudocyst, a common complication of acute or chronic pancreatitis, in rare instances may also extend to the mediastinum. A case of 67-year-old woman presenting with a triad of chest pain, dysphagia, and dyspnea is presented. The patient had an episode of acute alcoholic pancreatitis 1 year before presentation. Chest radiography on admission showed a retrocardiac opacity. Two-dimensional echocardiography revealed an echolucent mass compressing the left atrium. A subsequent upper gastrointestinal series for her dysphagia showed extrinsic compression of the distal esophagus. Finally a definitive diagnosis was made with computed tomography (scan), which revealed a 19 × 12 cm pseudocyst extending from the body of pancreas into the thorax and compressing the esophagus and the cardiac chambers. A mediastinal pseudocyst can cause symptoms due to compression or invasion of surrounding structures. The fluid collection may enlarge slowly and hence the symptoms can be delayed as in our patient. The pseudocyst was successfully treated using endoscopic ultrasound-guided transesophageal drainage. Approximately 50 cases of mediastinal extension of the pancreatic pseudocyst in the world literature are reported. At this time, this is only the second time that successful drainage of a mediastinal pseudocyst using a transesophageal approach under endoscopic ultrasound guidance has been reported. The literature was reviewed for clinical presentation, complications, and available treatment options for mediastinal pancreatic pseudocysts.

Case Report

A 67-year-old woman presented to the emergency department with a 3-month history of worsening chest pain and dyspnea. She also reported new-onset dysphagia, postprandial fullness, and a 10-pound weight loss. The chest pain was nonexertional in the retrosternal area and was more of a constant dull ache. She complained of dysphagia with solid foods such as steak for the previous 3 weeks. Her medical history was significant for gastritis, chronic obstructive pulmonary disease, and hypertension. Her medications included omeprazole, hydrochlorothiazide, and salbutamol and ipratropium bromide metered dose inhalers. A year previously, the patient had an attack of acute alcoholic pancreatitis after an alcohol binge for which she was hospitalized and discharged without any complications. At the time of discharge on that admission her amylase level was 88 mg/dL (normal, 28-100 mg/dL). She did not follow up with her primary care physician, continued to drink, and had occasional episodes of self-limiting pain for which she did not seek any treatment. At this admission, her vital signs included a blood pressure reading of128/80 mm Hg and heart rate of 90 beats per minute. She was afebrile, with 97% oxygen saturation on room air. In general, the patient was not in any acute distress. Cardiopulmonary examination was unremarkable. Her abdomen was soft, nontender with normal bowel sounds, and no organomegaly. Laboratory workup revealed a white blood cell count of 6700/cc, hematocrit of 36 g/dL, and platelet count of 250,000/cc. She had normal cardiac enzyme and electrolyte levels, and normal renal function panel results. The patient had an elevated amylase level of 149 mg/dL (normal, 28-100 mg/dL) and a normal lipase level at 35 mg/dL (normal, 0-60 mg/dL). Admission electrocardiogram revealed normal sinus rhythm without any changes suggestive of ischemia. Her liver enzyme levels were normal except for elevated aspartate aminotransferase of 72 mg/dL (normal, 14-33 mg/dL). Because angina was also a possibility, the patient underwent dobutamine stress echocardiography, which did not show any evidence of ischemia. Admission chest radiography revealed a retrocardiac opacity (Figure 1).

Figure 1.

Anteroposterior view of chest showing retrocardiac opacity (arrows).

Subsequent workup revealed a large echolucent area compressing the left atrium on the two-dimensional echocardiogram (Figure 2).

Figure 2.

Two-dimensional echocardiogram (apical 4-chamber view) showing compression of left atrium by an echolucent mass (arrow).

An upper gastrointestinal series that was performed for dysphagia was significant for compression of the distal esophagus by an extrinsic mass. An abdominal computed tomography (CT) scan showed a 19 × 12 cm hypodense cystic mass extending from the body of the pancreas into the thorax up to the subcarinal angle being posterior to the esophagus and anterior to the descending aorta. The cystic mass was compressing the distal esophagus, and possibly the cardiac chambers (Figure 3).

Figure 3.

CT scan showing mediastinal pseudocyst (PP) causing compression of esophagus (arrow).

Endoscopic retrograde cholangiopancreatography (ERCP) was performed, which showed normal ductal anatomy. There was no communication between the pancreatic duct and the pseudocyst on the ERCP. Because of the proximity to the major vessels and absence of a clear bulge inside the stomach or esophagus, endoscopic ultrasound (EUS)-guided transesophageal drainage of the mediastinal pseudocyst was performed through the lower third of the esophagus. Color Doppler was used before needle puncture to confirm the absence of significant vascular structures within the needle's path. Two passes were made with a 19-gauge needle via a transesophageal approach; 250 mL of serous amber fluid was removed. No drainage stent was left in place. The fluid had a very high amylase level (4980 mg/dL). The Gram stain and culture did not reveal any organisms. Tumor markers, CA19-9 and carcinoembryonic antigen, were within normal limits. She reported immediate improvement in her symptoms within a day after the procedure. The patient did have a 1-month and 3-month post-procedure follow-up in the gastroenterology outpatient clinic. She is asymptomatic and has gained 5 pounds since the drainage of the mediastinal pseudocyst.

Discussion

We report an unusual case of a large mediastinal pseudocyst causing compression of cardiac chambers as well as the esophagus and presenting with a triad of dysphagia, chest pain and dyspnea. The interesting features about our case were the delayed onset, large size, and successful drainage of the pseudocyst using EUS-guided transesophageal approach.

Pseudocyst formation is a common complication of both acute and chronic pancreatitis. Most pseudocysts occur in peripancreatic area and very rarely do they reach the mediastinum. Pancreatic pseudocysts are cystic cavities encased by reactive granulation or fibrous tissue, in or around the pancreas. The presence of a well-defined wall distinguishes a pseudocyst from an acute fluid collection seen in acute pancreatitis. The Atlanta classification is widely used to distinguish acute fluid collection from acute and chronic pseudocysts. Acute fluid collection appears early in the course of acute pancreatitis and lacks a wall of inflammatory tissue while acute pseudocysts are composed of pancreatic fluid enclosed by a wall of inflammatory tissue and occur as a result of acute pancreatitis or trauma to the pancreas. Chronic pseudocysts, although also composed of pancreatic fluid enclosed by a wall of inflammatory tissue, occurs only as a consequence of chronic pancreatitis without any attack of preceding acute pancreatitis.[1]

Pancreatic ductal obstruction due to stricture or stones leading to an elevated intraductal pressure, results in pseudocyst formation. Pseudocyst can complicate 7% to 15% of episodes of acute pancreatitis and 20% to 25% of cases of chronic pancreatitis.[2] Spontaneous resolution occurs in more than 50% of cases but complications can occur in up to 5% to 40% of cases as reported in various studies.[3] Common complications include infection, intracystic hemorrhage, enlargement, and mass effect causing bile duct or bowel obstruction and formation of internal or external fistula.[3] The natural history, etiology, complications, and definitive treatment of mediastinal pseudocysts is still evolving due to their rare occurrence. To our knowledge, there have been about 50 case reports in world literature of mediastinal extension of pancreatic pseudocyst.[4]

It is postulated that mediastinal pseudocysts are caused by rupture of the pancreatic duct posteriorly into the retroperitoneal space. The pancreatic fluid then tracks through the diaphragmatic hiatuses into the mediastinum. Diaphragmatic openings for the esophagus and aorta are the most common sites of entry into the posterior mediastinum.[5] Symptoms are primarily the result of compression or invasion of mediastinal structures and patients may present with dysphagia, pseudoachlasia, odynophagia, dyspnea, weight loss, and/or chest pain.[6]

The diagnosis of mediastinal pseudocyst should be suspected in a patient presenting with any of the above symptoms with a history of acute or chronic pancreatitis. A chest radiograph may be nondiagnostic but can show retrocardiac opacity as in our case. Definitive diagnosis was made in our case by a CT scan showing a thin-walled low attenuation cystic mass extending from the body of pancreas into the mediastinum. Contrast-enhanced CT scan has a very high sensitivity and can provide the details regarding the location as well as the anatomic relation of the pseudocyst to the surrounding structures. Magnetic resonance imaging and magnetic resonance cholangiopancreatography (MRCP) can help identify the connection between the mediastinal and abdominal pseudocyst in cases where it is not so evident on CT scan. MRCP has similar sensitivity to ERCP and has the advantage of providing images of the ducts in their natural state because it does not involve the distension of the ducts by the injected contrast media.[7] EUS is increasingly being used in evaluating cystic lesions of the pancreas given its advantages in delineating intracystic contents and wall structures.[8] An elevated amylase level in the aspirated fluid from a mediastinal pseudocyst confirms the diagnosis.[9]

It would be interesting to speculate the cause of mediastinal pseudocyst formation in our patient. She had presented a year earlier with alcoholic pancreatitis and was discharged after an uncomplicated course. Because there was no evidence of pancreatic calcification on CT and the ERCP did not show any ductal irregularities, we assume pseudocyst formation occurred as a complication of acute pancreatitis. It would have occurred after the first episode with which she presented or during one of the episodes of self-limiting pain that could possibly have been an episode of acute pancreatitis. The slowly progressive fluid collection may have delayed the onset of symptoms and hence the delay in seeking medical attention by our patient.

Complications due to mediastinal pancreatic pseudocyst can occur due to compression, invasion, or rupture of pseudocyst into surrounding structures besides infection and hemorrhage.[6] Lymphatic interstitial edema due to compression of lymphatic flow from lungs, with obstruction of the trachea or major bronchus resulting in respiratory compromise, and retrocardiac compression leading to elevated filling pressures causing congestive cardiac failure by the enlarging pseudocyst has been described in a few case reports.[10,11] A case of mediastinal pseudocyst eroding into the pericardial sac and presenting as life-threatening tamponade has also been reported in literature.[12]

Spontaneous regression of mediastinal pseudocysts is rare.[13,14] The treatment options for this entity are dictated by the severity of symptoms, the size of the pseudocyst, the ductal anatomy, and the surgical expertise available. Medical management is supportive and includes bowel rest, nutritional support, and stomatostatin analogues. Yasuda and colleagues reported complete resolution of pleural effusion and mediastinal pseudocyst with the use of octreotide.[15]The drug acts by inhibiting pancreatic secretions and thus facilitates closure of pancreatic fistula. In most of the cases before the year 2000, surgical drainage using open laparotomy or percutaneous drainage were the chosen treatment options.[4,11,16,17] Transcutaneous external drainage can be combined with CT-guided stent placement. Complications of external drainage include bleeding, infection, clogging of catheters, permanent fistula formation, and cyst recurrence. These drainage modalities for pseudocysts limited to the abdomen, in general, have a recurrence rate of 20% and a complication rate of 15%.[11] With the advancement in endoscopic techniques, endoscopic drainage is becoming the standard of care. Endoscopic internal drainage options available are ERCP with transpapillary duct drainage combined with endoscopic stent placement or transmural drainage. All endoscopic procedures for the treatment of pancreatic pseudocysts have recurrence of less than 5% and complication rate of 10%.[11] ERCP with transpapillary stent placement can be used only when the mediastinal pseudocyst communicates with the pancreatic duct. The concept behind this is the drainage of high pressure abdominal component helps in regression of the thoracic component. Transmural drainage can be achieved by transgastric, transesophageal, or transenteric approaches. Endoscopic ultrasound is increasingly being used to guide transmural internal drainage of mediastinal pseudocyst. It helps to identify wall thickness, the site to be punctured in a nonbulging pseudocyst as well as help avoid major vessels. As per our literature search, transpapillary approach for mediastinal pseudocyst drainage has been described in approximately 5 cases and transgastric drainage in 2 cases so far.[5,9,18–21]

To our knowledge, the transesophageal approach has only been described once before in world literature.[22] Thus this may be the second time that the successful use of the transesophageal approach is being reported. Open surgical drainage should be reserved for patients in whom pancreatic necrosis, abscess, hemorrhage, or rupture of pseudocyst occurs.[11] Various drainage approaches include cystogastrostomy or cystojejunostomy, Roux en Y pancreaticoduodenostomy, and pancreaticojejunostomy should be reserved for complicated cases.

Conclusion

Mediastinal pancreatic pseudocyst should be suspected in a patient presenting with atypical chest pain, dyspnea, or dysphagia, in the setting of a clinical history of pancreatitis. The timely and accurate diagnosis is important for this unusual and potentially life-threatening presentation of a common complication of pancreatitis. The finding of a thin-walled low-attenuation cystic mass in the posterior or middle mediastinum in continuity with pancreas and an elevated amylase level on analysis of the cystic content are required for definitive diagnosis. With the limited experience so far transmural drainage using transesophageal or transgastric approach under endoscopic ultrasound guidance appears to be a technically feasible, minimally invasive, and safe procedure for drainage of such mediastinal pancreatic pseudocyst. Physicians should be aware of atypical presentations and treatment options available for such mediastinal extension of a pseudocyst in a patient with a history of acute or chronic pancreatitis.