Solitary Main Pancreatic Ductal Calculus

Solitary Main Pancreatic Ductal Calculus of Possible Biliary Origin
Causing Acute Pancreatitis
Ramakrishna Prasad Chowdary Chaparala
1
, Rafiuddin Patel
1
, James Ahsley Guthrie
2
,
Mervyn Huw Davies
3
, Pierre J Guillou
1
, Krishna V Menon
1
1
Department of Academic Surgery,
2
Department of Radiology and
3
Department of Hepatology,
St. James University Hospital. Leeds, United Kingdom
ABSTRACT
Context Pancreatic ductal calculi are most
often associated with chronic pancreatitis.
Radiological features of chronic pancreatitis
are readily evident in the presence of these
calculi. However, acute pancreatitis due to a
solitary main pancreatic ductal calculus of
biliary origin is rare.
Case report A 59-year-old man presented
with a first episode of acute pancreatitis.
Contrast enhanced computerized tomography
(CT) scan and endoscopic retrograde
cholangiopancreatography (ERCP) revealed a
calculus in the main pancreatic duct in the
head of the pancreas causing acute
pancreatitis. There were no features
suggestive of chronic pancreatitis on CT
scanning. The episode acute pancreatitis was
managed conservatively. ERCP extraction of
the calculus failed as the stone was impacted
in the main pancreatic duct resulting in severe
acute pancreatitis. Once this resolved, a
transduodenal exploration and extraction of
the pancreatic ductal calculus was performed
successfully. Crystallographic analysis
revealed the composition of the calculus was
different to that seen in chronic pancreatitis,
but more in keeping with a calculus of biliary
origin. This could be explained by migration
of the biliary calculus via the common
channel into the main pancreatic duct.
Following the operation the patient made an
uneventful recovery and was well at two-year
follow up.
Conclusion Acute pancreatitis due to a
solitary main pancreatic ductal calculus of
biliary origin is rare. Failing endoscopic
extraction, transduodenal exploration and
extraction is a safe option after resolution of
acute pancreatitis.
INTRODUCTION
Pancreatic calculi are a feature of chronic
pancreatitis (CP). The most common cause
for CP in the UK is alcohol. Other causes of
CP are tropical, hereditary or idiopathic. The
prevalence of calculi cannot be separated
from the prevalence of the etiological factors,
the most common being alcohol [1, 2, 3, 4, 5,
6].
Sarles suggested that all forms of CP are
calculous disease irrespective of radiological
studies showing presence or absence of
calculi [2]. It is generally believed that
pancreatic calculi visible on radiography
usually occur in the late stages of chronic
pancreatitis [6]. More recently, abdominal CT
scanning has revealed a comparatively larger
number of intraductal calculi [6].
We wish to report a case of a solitary main
pancreatic duct (MPD) calculus of possible

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JOP. Journal of the Pancreas – http://www.joplink.net – Vol. 6, No. 5 –September 2005. [ISSN 1590-8577]
446
biliary origin causing acute pancreatitis with
no radiological features of CP in the
remainder of the gland.
CASE REPORT
A 59-year-old Caucasian man presented with
acute onset upper abdominal pain radiating
through to the back, associated with nausea
but no vomiting, following a large meal.
There was no history of alcohol intake. There
were no similar episodes of pain in the past.
The patient had a long standing history of
musculoskeletal back pain in the lower
thoracic area and had undergone facet joint
injections for pain relief. On examination the
patient was not jaundiced and was tender in
the epigastric region. The rest of the
examination was unremarkable.
Blood tests revealed an elevated amylase
serum level (greater than 1,000 IU/L;
reference range 0-110 IU/L), a leukocytosis
(23.7 x10
9
/L; reference range 4.0-11.0
x10
9
/L), hyperbilirubinemia (41 µmol/L;
reference range 5-21 µmol/L) and a normal
alkaline phosphatase. Abdominal ultrasound
scan demonstrated changes of acute
pancreatitis around the pancreatic head, with
no gallstones and normal caliber bile ducts.
Contrast enhanced abdominal CT scan
demonstrated an edematous and inflamed
pancreatic head, as well as an impacted stone
at the ampulla within the distal bile duct,
causing obstruction. The remainder of the
pancreas enhanced normally with no
associated features of CP (Figure 1). As the
scan suggested an impacted stone in the distal
bile duct at the ampulla, an ERCP was
performed.
Initial ERCP suggested a radio-opaque
calculus within the MPD in the head of the
pancreas, with no abnormality of the biliary
tree (Figure 2). Therefore, pancreatic duct
sphincterotomy was undertaken. Attempted
endoscopic extraction of the MPD calculus
was unsuccessful.
Following ERCP the patient had a further
attack of upper abdominal pain with an
increase in serum inflammatory markers.
Abdominal CT scan revealed severe acute
pancreatitis associated with sterile necrosis
within the head and body of the pancreas. The
patient was managed conservatively with
supportive therapy and nasojejunal feeding.
Following resolution of the acute episode 8
weeks after initial presentation, the patient
underwent a transduodenal exploration of the
pancreatic duct with extraction of calculus
(1x0.75 cm), pancreatic and biliary
sphincteroplasty and a cholecystectomy.
Crystallographic analysis of the calculus
revealed the composition to be pure calcite
with no amorphous or proteinaceous material,
which was not in keeping with typical
Figure 1. CT scan showing normally enhanced
pancreas with no features of chronic pancreatitis.
Figure 2. ERCP: radio-opaque calculus in the head of
the pancreas and not in the CBD.

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JOP. J Pancreas (Online) 2005; 6(5):445-448.
JOP. Journal of the Pancreas – http://www.joplink.net – Vol. 6, No. 5 –September 2005. [ISSN 1590-8577]
447
pancreatic calculi (Figure 3). The patient
made an uneventful recovery and has been
asymptomatic with no recurrence of pain or
pancreatitis for the past two years.
DISCUSSION
Pancreatic concretions have been a subject of
investigation since the 17
th
century. Since
they were described in 1667 by DeGraaf,
several workers have elaborated on their
clinical, biochemical, biophysical and
behavioral characteristics [6, 7].
Previously, two primary patterns of
calcification were believed to exist: an
intraductal pattern, representing true stones
and a parenchymal calcific pattern,
representing “false stones” or calcifications
[6, 8, 9]. The current consensus is that the
only mode of calcification in the excretory
portion of the pancreas is the formation of
intraductal calculi [10]. In the industrialized
nations of the West, alcoholism stands out as
the cause for chronic calcific pancreatic
disease [6]. Tropical pancreatitis is one of the
most common causes of CP in the developing
world [11].
In the present case, CT scans had suggested a
stone impacted at the ampulla, however this
was disproved at ERCP which revealed a 1
cm calculus in the MPD within the pancreatic
head. This was solitary with no calculi or
strictures in the remainder of the pancreatic
duct and no calcification within the
parenchyma. Despite this large solitary
calculus the patient had no previous episodes
of pancreatitis and no history of alcohol
abuse. He presented with a first episode of
acute pancreatitis, with no radiological
features of chronic pancreatitis.
A clue to the diagnosis of pancreatic calculi in
CP by ERCP is the presence of radiolucent
areas in the dilated MPD. The circular
translucent areas denote protein plugs or
precalcified stones [6]. Contrary to this, our
patient had a radio-opaque shadow in the head
of the pancreas on CT and ERCP. The lack of
amorphous material as revealed in the
chemical analysis of the calculus from this
patient may explain the radiological findings.
Studies have shown that stones in the
pancreas are formed primarily from calcium
carbonate, proteins and polysaccharides. They
may be single or multiple existing as small
concretions or well developed calculi 1 to 2
cm in diameter. A sliced section of a
pancreatic stone usually shows single or more
often multiple cavities, occupied by
proteinaceous material in vivo. The core is
composed of a very fine network of fibres
(amorphous substance). The outer shell shows
a wavy spiral pattern with small, tiny particles
scattered around. These particles represent
immature calcite crystals. The elemental
composition of calculi in patients from
different geographic regions appears to
remain the same [6].
Crystallographic analysis of the pancreatic
calculus in our case revealed no amorphous
material in the sample although it did show
calcite. This composition is distinct when
compared to the well known two layered
structure of pancreatic calculi seen in chronic
pancreatitis, thus suggesting a possible
different mechanism of lithogenesis. We
propose that the calculus may have originated
in the gallbladder and possibly migrated into
the MPD through the common channel. We
believe the calculus migrated at an earlier date
via the common channel and lodged in the
MPD, over time attaining the size of 1 cm.
Crystallographic analysis of the calculus
supports this hypothesis. Arguably, the point
against this hypothesis would be the absence
Figure 3. Crystallographic analysis of the calculus
composed of pure calcite with no amorphous or
proteinaceous material.

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JOP. J Pancreas (Online) 2005; 6(5):445-448.
JOP. Journal of the Pancreas – http://www.joplink.net – Vol. 6, No. 5 –September 2005. [ISSN 1590-8577]
448
of calculi in the gallbladder. However,
solitary biliary ductal calculi in the absence of
multiple gallstones have been described [12].
Endoscopic extraction, with or without
extracorporeal shock wave lithotripsy
(ESWL), is the preferred method of extraction
of MPD calculi [13]. However, failing this,
transduodenal exploration and calculus
extraction from the MPD is a safe procedure.
Received June 22
nd
, 2005 - Accepted July 1
st
,
2005
Keywords Lithiasis; Pancreatic Ducts;
Pancreatitis
Abbreviations CP: chronic pancreatitis;
MPD: main pancreatic duct
Correspondence
Krishna V Menon
Department of Academic Surgery
St. James University Hospital
Leeds LS 9 7 TF
United Kingdom
Phone: +44-0113.20.65122
Fax: +44-0113.20.66416
E-mail: kvmenon@aol.com
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