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1203

Pictorial

Filling Defects in the Pancreatic Retrograde Pancreatography Andrew

J. Taylor,1

Filling during

defects

Timothy

in the

endoscopic

J. Carmody,1

pancreatic

retrograde

duct

Michael

are

(ERP)

finding and

have

a variety of causes. Some filling defects may be artifactual or related to technical factors and, once their origin is recognized, can be disregarded. Others may be due to acute changes of pancreatitis and should prompt more careful injection of contrast material

into

the

or a neoplasm, intervention.

duct. either

The

exact

Intraluminal of which nature

may

masses

may

require

surgery

of these

filling

represent

defects

Duct on Endoscopic

J. Schmalz,2

a frequent

pancreatography

calculi

or endoscopic may

not

be

apparent on radiographs, and other studies may be needed. This article reviews our approach to the evaluation of filling defects in the pancreatic duct.

Artifacts The most common intraluminal filling defect is the injected air bubble. Although the catheter should be cleared of all air by aspiration or flushing before injection, occasionally some air remains in the catheter and is introduced into the pancreatic duct when contrast material is injected. These air bubbles are usually easily recognized by their round or slightly oval shape, conforming to the shape of the duct. They are often multiple and contiguous in distribution (Fig. 1). At fluoroscopy, air bubbles may be seen to move easily with injection of a small amount of contrast material, or may be visualized as they are injected from the catheter tip. They can be aspirated back into the catheter. As the patient’s position is altered, air bubbles in the pancreatic duct will rise to the

Debra

A. Wiedmeyer,1

December

1992 0361-803X/92/1596-1203

© American

and

Edward

T. Stewart1

highest portion of the duct. A large column of air may interfere with complete opacification of the main pancreatic duct, and acinarization of the pancreas may occur as more contrast material is injected to fill the air-locked segment. The presence of air in the pancreatic duct also can simulate a stricture or be mistaken for a ductal obstruction. Contrast material extravasated during injection may mimic an enlarged, distorted pancreatic duct filled with an irregular intraluminal mass (Fig. 2; compare with Fig. 1 1). Although infrequent, extravasation usually occurs when seating the catheter tip within the pancreatic duct before injection is difficult, or after unintentional cannulation of a side branch of the pancreatic duct. Inflammation Inflammation

of the pancreas may result in many different filling defects. The most common defects are pancreatic duct calculi. Proteinaceous plugs are associated with chronic inflammation of the pancreas. Invariably, these plugs accrue calcium carbonate and develop into calcified intraductal stones, a relatively late finding seen in chronic calcific pancreatitis. At ERP, these foci may or may not show calcification, depending on their stage of development. A preliminary radiograph is helpful in showing calcification of these stones, which may be obscured by subsequent injection of contrast material. CT has a higher sensitivity in defining subtle calcifications in the pancreas (Fig. 3). An-

types of intraductal

Received April 2, 1992; accepted after revision May 1 9, 1992. Presented in part at the annual meeting of the Society of Gastrointestinal Radiologists, Orlando, FL, February 1992. 1 Department of Radiology. Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, 9200 W. Wisconsin reprint requests to A. J. Taylor. 2 Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226. AJR 159:1203-1208,

Essay

Roentgen

Ray Society

Ave.,

Milwaukee,

WI 53226.

Address

TAYLOR

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1204

Fig. 1.-Air bubbles. Endoscopic retrograde pancreatogram in a man with suspected pancreatic mass shows four filling defects (straight arrows) in proximal body of pancreatic duct. Note round and oval appearance of four masses contiguously arranged within duct. At tip of catheter, an air bubble is being injected (curved arrow). Also note draping of duct of Santorini from a mass in pancreatic head (arrowheads).

ET AL.

Fig. 2.-Extravasation A, Seating of cannula

injection

of contrast

of contrast material simulating a mass. before injection of contrast material into pancreatic

material,

it is unclear

whether

endoscopic

December

1992

duct was difficult.

After

pancreatogram

(ERP)

retrograde

shows pancreatic head to have a large, distorted duct filled with a mass, or if this appearance is related to extravasation. Presence of a nonobstructed duct proximally suggests a technical cause. B, 3 months later, ERP shows diffuse narrowing of distal duct due to chronic pancreatitis with no mass present. Appearance of duct at this examination was similar to that seen at ERP 1 year earlier.

Fig. 3.-Correlation of CT and endoscopic retrograde pancreatographic (ERP) findings pancreatectomy for chronic alcoholic pancreatitis presented with increasing pain. A, ERP shows a filling defect (arrow) in distal portion of pancreatic duct just proximal

this injection

AJR:159,

in diagnosis to a stricture.

of pancreatic

calculi.

The technologist

A patient

had changed

who

had had partial

syringes

just before

so an air bubble may have been introduced.

B, ERP obtained after patient had been C, CT scan shows a small calcification tiny, intraductal stone.

rotated (arrow)

still shows a filling defect (arrows), in head of pancreas corresponding

gular borders, multiplicity, and mobility may differentiate calculi from other filling defects (Fig. 4). When ductal stones are thought to be the cause of abdominal pain, surgery or endoscopic intervention may be appropriate to relieve the obstruction of the pancreatic duct. A more unusual finding in chronic inflammatory disease of the pancreas is the presence of a gelatinous cast within the main pancreatic duct. Although such casts are usually associated with some neoplasia, we have noted two such cases associated with pancreatitis (Figs. 5 and 6).

which is now smaller. to location of intraductal

defect,

thereby

confirming

diagnosis

of a

Rarely, numerous small filling defects are seen in the main pancreatic duct in patients with acute pancreatitis (Fig. 7). Although ERP is contraindicated in the acute phase of pancreatitis, the pancreatic duct may be inadvertently injected during an attempt to visualize the common bile duct to check for choledocholithiasis as a cause for the pancreatitis. These filling defects are thought to be related to debris from pancreatic autodigestion. When pancreatitis is associated with formation of pseudocysts, the pseudocyst will fill with contrast material during

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AJA:159,

December

FILLING

1992

DEFECTS

Fig. 4.-calculi of chronic pancreatitis. Endoscopic retrograde pancreatogram shows findings of irregular and ectatic duct with clubbing of side branches, typical for chronic pan-

creatitis.

In addition,

(straight arrows) these with large, tip of catheter.

in both smooth

multiple

faceted

stones

head and tail of pancreas. air bubble (curved arrow)

A

are

seen

Compare just above

IN PANCREATIC

1205

DUCT

Fig. 5.-Gelatinous cast associated with chronic pancreatitis. A 57-year-old patient with a history of alcohol abuse 20 years earlier had clinical signs and symptoms of chronic pancreatitis for 2 years. A, Endoscopic retrograde pancreatogram (ERP) shows a long intraluminal cast (arrowheads) during initial injection of contrast material. Tip of cannula is seen (arrow). B, Subsequently, ERP shows a balloon-tip catheter (straight arrow) placed proximal to cast (curved arrow) that eventually is withdrawn from duct. A subsequent CT scan (not shown) was unremarkable. At surgery for sphincterotomy, the pancreas showed evidence of pancreatitis but no mass lesion. The patient was asymptomatic 18 months later.

B

C

Fig. 6.-Gelatinous cast associated with chronic pancreatitis in 34-year-old man with a 3-year history of chronic pancreatitis. A, Endoscopic retrograde cholangiogram after initial injection of contrast material into pancreatic duct suggests ductal obstruction (arrow) near junction of body and tail. B, In an attempt to better define area of cutoff and to ensure adequate filling, a guidewire was passed to advance a catheter near presumed site of obstruction. A radiograph obtained during guidewire placement shows tip of guidewire advancing into more proximal, nonopacified part of duct. c, Eventually, a balloon tip catheter was placed into nonopacified segment of duct. A radiograph shows part of gelatinous mass being removed (arrow). At subsequent surgery, pancreas had changes of chronic pancreatitis. Pathologic examination of resected pancreatic tail showed no evidence of malignancy.

injection at ERP approximately 70% of the time [1 J. Although care must be taken not to overinject the pseudocyst, filling defects due to blood clot or debris can be visualized with contrast material partially filling the cavity (Fig. 8). Neoplasia Intraductal filling defects plasms are unusual. These

associated intraductal

with pancreatic foci are related

neoeither

to the tumor itself or to the associated secretion of a gelatinous cast. Benign intraductal masses are rare. The intraductal papilloma is probably the most common benign intraductal tumor (Fig. 9). It may be single or multiple and may be associated with hypersecretion of mucin. The most common malignant pancreatic tumor, ductal adenocarcinoma, is usually associated with ductal stricture or amputation. However, on occasion, it may appear as an

1206

TAYLOR

ET AL.

AJR:159,

December

1992

Fig. 7.-Filling defects seen in acute pancreatitis. Endoscopic retrograde cholangiogram of a 27-year-old patient with acute pancreatitis was obtained to check for a gallstone in common bile duct. Contrast material was inadvertently injected

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into pancreatic numerous with acute

duct.

filling defects pancreatitis.

This

examination

that

can

shows

be associated

Fig. 8.-Filling defect within a pseudocyst. Endoscopic retrograde pancreatogram shows large, angular filling defect (straight arrow) in pseudocyst (curved arrows), which fills off head of pancreatic duct. Other findings of chronic pancreatitis are seen in more proximal part of duct.

Fig. 9.-Probable benign intraductal papilloma. A, Initial pancreatogram shows a small, smooth, stationary defect (arrow) in distal part of pancreatic duct. B and c, To further define small mass, a brush biopsy was done (B), and forceps biopsy was attempted (C), during time of initial study. No malignant cells were found. Lack of change seen on endoscopic retrograde pancreatography over 18 months suggests a benign mass compatible with an intraductal papilloma.

Fig. 10.-Intraductal pancreas.

adenocarcinoma

of

A, Endoscopic retrograde pancreatogram (ERP) shows a focal, mildly irregular mass (arrow) projecting into pancreatic duct. Results of brush cytology were unrevealing. B, Follow-up ERP 9 months later reveals enlargement of mass with obliteration of ductal segment. Malignant cells were obtained at this time. Adenocarcinoma was found at surgery.

AJR:159,

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Fig.

December

FILLING

1992

1 1.-lntraductal

adenocarcinoma

DEFECTS

IN PANCREATIC

DUCT

1207

of

pancreas. A, At endoscopic retrograde pancreatography, injected contrast material courses between filling defects, which expand distal duct. Marked enlargement of duct with immobile filling defects suggests contrast material coursing through crevices of intraductal mass rather than between numerous faceted calculi. B, Photomicrograph of surgical specimen correlates directly with pancreatogram, showing markedly dilated distal portion of pancreatic duct (arrowheads) and intraductal tumor (straight arrows). Curved arrow points to papilla for orientation. (H and E, original magnification x5)

Fig. 12.-Mucinous

cystic pancreatic

neoplasm.

A, Endoscopic retrograde pancreatogram initially shows a mass (arrows) protruding into pancreatic duct. B, With further injections, a cavity begins to fill with contrast material (arrowheads). Communication between mucinous cystic neoplasm and main pancreatic duct is unusual. C, CT scan 1 day later shows multiple cysts with large, solid component in pancreatic head (arrows). Other CT scan helped to better define large cysts of this mass, suggesting a macrocystic cystadenoma or cystadenocarcinoma. At surgery, a mucinous (macrocystic) cystadenocarcinoma was resected.

intraductal

filling defect, either as a polypoid mass (Fig. 10), to the intraductal papilloma (compare Figs. 9 and 1 0), or as a large, irregular growth expanding the main pancreatic duct (Fig. 1 1 ). Rarely, adenocarcinoma will occur with mucinous hypersecretion in association with a plaque or polypoid lesion [2]. A mucin-filled pancreatic duct is most often associated with mucinous cystic neoplasms of the pancreas. As with other hypersecretory tumors, the excessive gelatinous material can cause dilatation of the main pancreatic duct with extension into the ampullary segment or even the distal portion of the common bile duct. The associated pancreatic mass may not be visible at ERP, and correlation with CT or sonography is important. However, the cystic mass may be apparent at ERP because of draping, narrowing, or total obstruction of the main pancreatic duct. Some abnormality is seen at ERP in

very similar

approximately 60% of cases [3]. As opposed to the inflammatory pseudocyst of pancreatitis, communication between the pancreatic duct and the cystic neoplasm is unusual but does occur (Fig. 1 2). The serous cystadenoma (microcystic adenoma), the other common cystic neoplasm of the pancreas, rarely shows communication with the pancreatic duct and therefore is not associated with intraductal filling defects. This lack of communication probably is due at least in part to the incomplete network of fibrous strands surrounding the tumor, which separates it from the pancreatic parenchyma. As with mucinous cystic tumors, some mass effect involving the ductal system may be present. A variation of a mucinous cystic neoplasm is the ductectatic mucinous cystadenoma or cystadenocarcinoma. By far, the most common appearance at ERP is dilatation of the uncinate branch, which is filled with mucinous casts (Fig. 1 3). Some

TAYLOR

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1208

Fig. 13.-Ductectatic

mucinous

cystadenoma

in a 78-year-old

ET AL.

woman with abdominal

AJA:159,

December

1992

pain.

A, Endoscopic retrograde pancreatogram shows markedly dilated uncinate branch with a long serpentine filling defect. This finding is typical for ductectatic tumors. B, During endoscopy, some of mucinous cast was obtained and sent for cytologic examination. Photomicrograph shows a fragment of tissue (straight arrows) with papillary excrescences that had been shed into duct. Goblet cells (curved arrow), which produced mucinous cast, are present. Radiologic and pathologic findings suggest a ductectatic mucinous cystadenoma. Of course, because of sampling error, this could still be a malignant lesion. Because of patient’s age and health, she was treated with a pancreatic stent. (Papanicolaou’s stain, original magnification x400) C, CT scan obtained 1 day later shows “cysts” (arrows) in uncinate process of pancreas representing a cross section through markedly dilated uncinate branch of pancreatic duct.

filling defects may be related to small papillary tumors. These dilated ducts are lined by a papillary hyperplastic epithelium that may be atypical or even frankly malignant. The abundant amount of mucus secreted by this epithelium produces the findings at ERP. Retrieval of the mucinous material from the duct during endoscopy can be helpful in providing cells for histologic diagnosis (Fig. 1 3B).

REFERENCES 1 . O’Connor

M, Kolars J, Ansel UL, et al. Preoperative endoscopic retrograde cholangiopancreatography in the surgical management of pancreatic pseudocysts. Am J Surg 1986:1 51 :18-24

2. Itai Y, Kokubo T, Atomi Y, Kuroda A, Haraguchi

Y, Terano A. Mucin-

hypersecreting carcinoma of the pancreas. Radiology 1987:1 65: 51-55 3. Warshaw AL, Compton CC, Lewandowski K, Cardenosa G, Mueller PA. Cystic tumors of the pancreas. Ann Surg 1990:212:432-445