We present here a case of disconnected pancreatic duct syndrome (DPDS), highlighting
the useful role of magnetic resonance cholangiopancreatography (MRCP) in depicting
this complication of acute necrotizing pancreatitis (ANP) and the necessity of heightened
awareness of radiologists to pick up this diagnosis.
A 36-year-old male patient with a history of chronic abdominal pain secondary to alcoholic
pancreatitis, complicated by walled-off pancreatic necrosis, underwent laparotomy
with necrosectomy about 6 months ago. A percutaneous drain (PCD) tube was placed during
surgery. The patient now presented with complaints of persistent drain output of about
100 mL/day for the past 6 months. At the time of presentation, the patient had no
fever, vomiting, abdominal tenderness, or rigidity. The blood workup showed normal
white cell count of 7.6 ×109/L (normal 4–11 × 109/L), normal serum amylase 52 U/L (normal 40–140 U/L), and mildly elevated lipase levels
86 U/L (normal 7–60 U/L). PCD output showed significantly elevated amylase and lipase
levels of 29,090 and 37,670 U/L, respectively.
Initially an ultrasound scan of the abdomen was performed, which revealed multiple
peripancreatic fluid collections. The patient was subjected to MRCP in a 3 Tesla magnetic
resonance imaging scanner (Skyra, Siemens Healthineers, Erlangen, Germany). Standard
institute protocol was followed and signal acquisition done using body coil. The sequences
used include three-dimensional (3D) space T2 (repitition time, TR 2400 ms; time to
echo, TE 698 ms), T2-weighted half-Fourier acquisition single-shot turbo spin-echo
(HASTE) axial and coronal sequences (TR 1200 ms, TE 100 ms), true fast imaging with
steady-state free precession, and Dixon sequences. HASTE sequence with fat suppression
and thick collimation slab was obtained in the coronal plane. It revealed a mildly
atrophic body and tail of pancreas ([Fig. 1]). Main pancreatic duct (MPD) was visualized for a length of 1.8 cm from the ampulla.
A focal discontinuity of MPD was seen in body of pancreas, measuring about 4.3 cm
([Fig. 2]). MPD in distal body and tail of pancreas was irregularly dilated with multiple
prominent side branches. PCD tube was noted with tip anterior to tail of pancreas
([Fig. 3]), with peripancreatic fat stranding. These features were consistent with DPD.
Fig. 1 True fast axial imaging showing the pancreas with irregularly dilated main pancreatic
duct in distal body and tail region (arrow).
Fig. 2 (A) Half-Fourier acquisition single-shot turbo spin-echo coronal image showing the main
pancreatic duct (MPD) in head region (green arrow) draining into ampulla, prominent
common bile duct (yellow arrow), and a nonvisualized segment of MPD (double arrow)
measuring 4.3 cm. (B) Dilated upstream MPD and its branches (blue arrow) seen separated from the proximal
pancreatic parenchyma with abrupt cutoff at nonvisualized portion, likely draining
into the peritoneal cavity.
Fig. 3 Volume rendered image showing the normal caliber proximal main pancreatic duct (MPD)
communicating with duodenum (blue arrow), dilated disconnected pancreatic duct in
distal body and tail (yellow arrow). Nonvisualized segment of MPD (red arrow). Tip
of percutaneous drain tube seen (arrowhead) near the disconnected segment, likely
draining the secretions of the distal viable pancreas.
Endoscopic retrograde cholangiopancreatography (ERCP) and stenting were attempted
twice, but failed. The patient was taken up for laparotomy, which revealed a plastered
upper abdomen with dense adhesions. A fistulous tract was seen extending from PCD
entry site to inferior surface of pancreas, near the tail region, traversing the transverse
mesocolon. Adhesions were released, and distal pancreaticosplenectomy was done. The
drain tube amylase dropped on postoperative day 10.
In DPDS, there is a circumferential disruption of the continuity of the pancreatic
duct resulting from an area of cellular necrosis.[1] This compromised ductal integrity leads to extraductal leakage of pancreatic secretions
and destruction of viable pancreatic tissue surrounding the duct, and the viable upstream
portion of the gland gives rise to the DPDS. The prevalence of DPDS is unknown but
studies have shown that ANP can be complicated by DPDS in 16 to 44% of cases.[2]
[3]
[4]
The typical clinical presentation includes persistent external pancreatic fistula,
recurrent pseudocyst, pancreatic ascites, region of walled off necrosis, or obstructive
recurrent acute or chronic pancreatitis of the upstream pancreatic parenchyma.[5] To confidently diagnose DPD, it is necessary to demonstrate all of the following
features: (a) necrosis of at least 2 cm of pancreas, (b) viable pancreatic tissue
upstream (i.e., toward the pancreatic tail) from the site of necrosis, and (c) extravasation
of contrast material injected into the MPD at pancreatography.[6]
The imaging methods used include contrast-enhanced computed tomography (CECT), along
with ERCP, MRCP, and endoscopic ultrasonography. To aid the diagnostic process, it
is possible to measure amylase levels in the drain output in patients with percutaneously
drained fluid collections. A drain amylase content greater than three times the serum
amylase levels may raise the suspicion of a fistula.[7]
The reference method for confirming the diagnosis has been ERCP, but being an invasive
procedure with a risk of complications, its indications are limited. Furthermore,
it fails to show the upstream pancreatic duct and cannot differentiate between a high-grade
stenosis and a disconnected duct.[1] In this respect, MRCP is far more appropriate.
MRCP done using secretin is an emerging imaging study of choice to diagnose a DPD,
which shows a cutoff of the downstream pancreatic duct with enhancing upstream pancreatic
parenchyma.[8] However, secretin MRCP is not widely available and 3D MRCP is a useful technique
to depict the DPD in most instances, as in our case. The main advantage of MRCP is
that it can evaluate both the MPD and the pancreatic parenchyma at the same time in
contrast to CECT combined with ERCP
Most peripancreatic collections following acute pancreatitis are treated conservatively
or with guided drainage. In the absence of infection, surgery is not usually contemplated.
The most common reason for delayed or missed diagnosis is a lack of awareness and
general unfamiliarity among treating physicians and radiologists. A timely and accurate
diagnosis of pancreatic duct disruption and disconnection can prevent complications,
particularly fistula formation and need of unnecessary drainage procedures, thereby
reducing the morbidity.[9]
