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Massive pleural effusion

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Q1: What is the most probable cause for the massive pleural effusion?

The most probable diagnosis is pancreaticopleural fistula due to chronic alcoholic pancreatitis.

Q2: How should the diagnosis be confirmed?

The diagnosis is based on a high index of suspicion in patients suffering from chronic pancreatitis and pleural effusion. The diagnosis is usually based on a triad of1-3:

1. A massive and recurrent pleural effusion (fig 1; p 536).

2. An extremely high pancreatic isoamylase level in pleural fluid (in this case it was 4771 IU/l at admission and rose to 25190 IU/l five days later).

3. An exudative pleural effusion with protein content above 30 g/l (in this case it was 56 g/l).

The diagnosis is usually confirmed by computed tomography, or on endoscopic retrograde cholangiopancreatography (ERCP), which may show the fistula connection to the pleural cavity. The sensitivity of the computed tomography is enhanced if undertaken immediately after ERCP.4 Contrast injection into the pleural collection may also be used to image the fistula tract.5 In our case ERCP failed to opacify the pancreatic duct due to tight stricture but revealed a benign stricture due to chronic pancreatitis at the distal end of common bile duct, which was stented during the procedure.

Q3: What would be the differential diagnosis?

The commonest differential diagnoses include:

1. Pleural effusion due to acute pancreatitis. The effusion is usually small, self limiting, and the pancreatic isoamylase level rarely exceeds 4000 IU/l.2 6

2. Pleural effusions are also seen with a range of malignancy, most commonly arisingfrom lung, breast, and ovarian cancers. Such effusion generally contains salivary isoamylase with a low concentration of only 200–400 IU/l.7

3. The pleural collection in oesophageal perforation also contains salivary isoamylase and food particles.8 The diagnosis can usually be confirmed radiologically with a contrast swallow.

Q4: What are the options for treatment?

The treatment of pancreaticopleural fistula remains controversial. Once the diagnosis has been confirmed, usually by pleural fluid amylase and protein elevation, the management can be either conservative or operative. Initial conservative measures have a considerable support in the literature.2 3 9

The principles of conservative treatment include:

1. Correction of fluid and electrolytes.

2. Maintenance of adequate nutrition with enteral feeding but total parenteral nutrition may be required for patients with malabsorption and ongoing catabolic status.

3. Adequate drainage of pleural cavity with multiple thoracocenteses or tube thoracostomy.

4. Early treatment of infection using an appropriate antibiotic, together with drainage of abscess, percutaneously or surgically, if required to prevent the development of sepsis.

5. Octreotide is a long acting synthetic analogue of somatostatin. It inhibits pancreatic exocrine and endocrine secretion and relaxes intestinal musculature. As an adjuvant to standard conservative fistula management it reduces fistula output, but whether it shortens the time for fistula closure remain to be proved by a well designed comparative study.10 Approximately 40%–60% of fistulas close spontaneously when the principles of conservative management are meticulously followed. It is emphasised, however, that surgery may be required for underlying pancreatic disease, in this regard close surveillance of these patients is necessary.2 3 9

In cases where fistula closure is not achieved with conservative treatment, an emerging role for ERCP has become evident. Pancreatic duct stricture is frequently found in a patient with pancreaticopleural fistula and successful results have been reported for fistula closure after endoscopic placement of stent. Transpapillary pancreatic duct stenting may remove the back pressure effect of stricture, stone and sphincter of Oddi, thus improving pancreatic duct drainage and enhance fistula closure. Long term follow up is needed before its role can be more accurately defined.11 12

Surgical treatment is indicated when non-operative management fails and in the presence of life threatening complications. The site of the fistula and presence of pancreatic duct stricture3 13determine the nature of the surgery. Hence the importance of preoperative evaluation with computed tomography and ERCP to define pancreatic duct anatomy. If ERCP is unsuccessful, operative pancreatography should be performed at the time of surgery. This can be either by cannulating the ampulla through a duodenotomy, or by a retrograde technique after amputating the tail of the gland.3

Surgery is generally safe and effective.2 Distal pancreatic resection is indicated when the pancreaticopleural fistula arises from the body or tail of the pancreas, provided the proximal pancreatic duct is patent. Internal drainage by Roux en-Y pancreaticojejunostomy or pseudocystojejunostomy is generally indicated for fistula arising, respectively, from the head of pancreas and in presence of a large pseudocyst not amenable to resection.2 3 13

In chronically ill patients who represent a high anaesthetic risk and whose fistula did not respond to conservative treatment, a short course of radiotherapy may be considered.14

Discussion

Pancreaticopleural fistula is a rare complication of chronic pancreatitis and occurs in fewer than 1% of patients after pancreatitis and around 3% of patients with a pancreatic pseudocyst.2 15 Chronic alcoholic pancreatitis is the commonest cause of pancreaticopleural fistula, reported in up to 80% of cases. The typical patients are young male alcoholics.1-3 Pancreaticopleural fistula is associated with a substantial mortality of 5%–10%, primarily from sepsis.2 3 16

Pancreaticopleural fistula occurs when the pancreatic duct or one of its branches is disrupted by chronic inflammation. The resulting leakage of pancreatic fluid may communicate with the pleural cavity to form a fistula with subsequent pleural effusion (usually left sided).1-3

The clinical manifestation is often misleading, since about 48% of patients do not have a clinical history of pancreatic disease. Moreover, patients with pancreaticopleural fistula present more commonly with chest than abdominal symptoms due to the large size of the pleural effusion and the indolent nature of their pancreatic disease.2 3 17

Chest symptoms are variable; patients present most commonly with dyspnoea but they may present with pleuritic pain, wheezing, and coughing.

Abdominal symptoms are absent in 18% of patients but epigastric pain radiating to the back is commonly seen.2 Postprandial pain, weight loss, and abdominal distension due to ascites may also be observed. Pericardial effusion and cardiac tamponade have also been reported. Some patients develop subcutaneous fat necrosis producing white nodule lesions on the trunk or the lower limb.2 3

Final diagnosis

Pancreaticopleural fistula secondary to chronic alcoholic pancreatitis.

References

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