THREE-DIMENSIONAL RECONSTRUCTION OF THE PANCREATIC DUCTS IN CHRONIC PANCREATITIS

Transcription

1 GASTROENTEROLOGY Copyright 1972 by The Williams & Wilkins Co. Vol. 62. No.5 Printed in U.S.A. THREE-DIMENSIONAL RECONSTRUCTION OF THE PANCREATIC DUCTS IN CHRONIC PANCREATITIS K. NAKAMURA, H. SARLES, AND H. PAYAN Unite de Recherches de Pathologie Digestive, Institut National de la Sante et de la Recherche Medicale, Marseille, France A three-dimensional reconstruction of the pancreatic ducts has been made from the secondary branches of the main duct to the terminal acini. This has been carried out by cutting serial sections from surgical specimens of the pancreas from 10 patients with alcoholic calcifying chronic pancreatitis, specimens from 2 patients with a small carcinoma obstructing the main pancreatic duct, and a normal pancreas. The lesions of calcifying pancreatitis demonstrated by this method showed characteristically: (a) spotty distribution of the lesions which were related to the ducts; (b) a frequent finding in the ducts of plugs of precipitated protein, which tended to evolve into calculi by deposition of calcium on their surface (these plugs rarely contained mucopolysaccharide); (c) all sizes of duct were involved and showed irregular dilation, loss of lining epithelium, encroachment of periductal connective tissue to form stenosis, pancreatic cysts or complete disappearance of acini, and ducts in the territory drained by a blocked duct. In chronic pancreatitis secondary to an obstruction in the main pancreatic duct, the lesions are different in almost every respect from those described above. In previous studies, 1, 2 we have shown that, in patients with chronic calcifying pancreatitis, the histological lesions differed little from 1 case to another and were quite distinct from the lesions seen in chronic pancreatitis secondary to obstruction of the duct of Wirsung. In the former group, the lesions at the beginning of the disease were spotty and affected one or more lobules which were surrounded by normal parenchyma. The le- Received June 21, Accepted December 18, Address requests for reprints to Dr. Henri Sarles, Unite de Recherches de Pathologie Digestive, Institut National de la Sante et de la Recherche Medicale, 46, chemin de la Gaye, 13-Marseille (ge) France. Dr. Nakamura's present address is: 427 Oto Yono-Shi, Saitama, Japan. Dr. Payan's present address is: Laboratoire d'histologie de la Faculte de Medecine, Marseille. France. 942 sions themselves showed partial or complete dilation of the acini and the intralobular canals with both intra- and perilobular fibrosis. Some of the ducts were obstructed by deposits of protein which tended to calcify at a later stage of the disease, thus forming calculi. In this early stage of the disease, the main pancreatic duct was seen to be normal. In advanced stages, fibrosis extended throughout the gland, but the focal lesions maintained their characteristic appearance, the lobules were variously affected, and some remained normal. It was at this advanced stage that dilation of the main pancreatic duct was seen. Chronic pancreatitis in which this type of lesions is present appears to be clinically and etiologically distinct from other forms of the disease. In a series of 100 patients, 93 were male and of the 55 in which the amount of alcohol consumed was known, 44 drank abnormal amounts (100

2 May 1972 THREE-DIMENSIONAL RECONSTRUCTION OF PANCREATIC DUCTS 943 ml of pure alcohol per day or more).2 Gallstones appeared in only 2 patients. Calcification of the pancreas was present in all but 6 cases, and in 5 of them it appeared later; for these reasons, we propose to call this condition primary calcifying chronic pancreatitis (PCCP). We have made a three-dimensional study of the ductal and acinar lesions. Material and Methods 1. Out of 13 specimens studied by serial section, 10 were obtained surgically, from patients with alcoholic chronic calcifying pancreatitis, by unroofing the anterior surface of the duct of Wirsung prior to pancreaticojejunostomy (5 cases), from a pancreaticoduodenectomy (2 cases), and after resection of the tail of the pancreas (3 cases). All of these 10 patients imbibed at least 100 ml of absolute alcohol daily and had severe persistent upper abdominal pain and weight loss. Three were diabetic. Secretin test showed mild to severe depression of volume or bicarbonate, or both. In addition, two specimens were obtained 3 hr postmortem, from behind a slow-growing carcinoma of the head of the pancreas from 2 patients with pancreatitis, and one was obtained after operation from a patient with a normal pancreas. In each instance, the specimens were fixed immediately in Bouin's solution or 10% formalin. Serial sections of the fragments of pancreas, 7.5 to 12.5 JIm in thickness, were made. The number of sections varied from 120 to 1097 (mean 800). The sections were stained with hematoxylin-eosin-saffron, and were counterstained by Von Kossa's technique to demonstrate calcification and with periodic acid-schiff to identify mucopolysaccharide. A paper tracing was made of each section by means of a projecting microscope. The plane of reconstruction could be chosen to give the best perspective of the canal. 3 The tracings were superimposed at intervals to make a model of the duct. The pathway of the duct was then drawn from the model on a plane parallel to its axis. 2. Polyvinyl was injected into the canal of Wirsung in two normal pancreases removed 2 hr after death and, in addition, in the pancreas from a patient with calcifying pancreatitis. In this way, casts of the ductal system were obtained. Results 1. Spatial reconstruction in PCCP. A. The irregularity of the distribution of these lesions confirms previous findings. Figure 1 shows a specimen of resected pancreas between the canal of Wirsung and the anterior surface of the gland. Two canals have been reconstructed as far as the acini. Canal A compared to the normal pancreas is normal in every respect including the acini which it drains. In contrast, canal C has an irregular lumen with periductal fibrosis while two of its lateral branches contain protein plugs. B. The distribution of the lesions is related to the ducts. Thus it is neither related to the blood vessels nor is completely random (fig. 1). Fibrosis is related to abnormal ducts and extends along the entire length and along the lateral branches or, alternatively, in short localized segments of such ducts. C. Involvement of the interlobular ducts. 1. The abnormal ducts were generally dilated and irregular in caliber. The sections cut at right angles to the axis of the ducts show that this distortion may be very striking. It is possible, however, that these changes are exaggerated by surgical manipulation which may allow fluid under pressure within the ducts to escape and the ducts themselves to retract. Dilation can develop throughout the smaller ducts in the gland. This may be localized behind an obstruction due to stenosis or to protein plugs whether calcified or not. However, such widespread dilation of smaller ducts is often seen without detectable obstruction in large ducts and in general the secondary ducts open into the duct of Wirsung without obstruction. The duct mucosa is either normal or cuboidal and may show inconstant zones of papillary hyperplasia or many-layered epidermoid stratification; but these types of metaplasia are scarce and frequently not found in a pathological duct (as for instance duct C, fig. 1). 2. Protein plugs may not be present in an individual section but are always found in three-dimensional reconstructions. These plugs are typically concentric laminar concentrations of protein. Many of these plugs are calcified. Calcification begins at the periphery. The fact that only one out of five plugs in our speci-

3 FIG. 1. This figure and figures 3 and 5 represent the projection of a reconstructed duct in a plane parallel to its axis, yet at right angle with Wirsung. Cross-hatched areas, fibrosis; squared areas, protein plugs within ducts; stippled areas, lobules in which the normal features are partially or completely preserved. The solid or dotted lines represent the walls of the ducts. In the enlarged insets, the thickness of a line represents the breadth of the epithelium. When the wall of the duct is indicated by a dotted line, the drawings in solid line which cross their path represent the contours of the duct in the section at this level, which is thus shown on a plane perpendicular to that of the actual drawing. The arrows indicate ducts which have been followed-up as far as their point of origin in lobules which have partially or completely preserved their secretory character. A specimen (b) from a patient with early calcifying pancreatitis was obtained by unroofing the pancreas (a). The details of secondary ducts at position A is shown in drawing c, and of duct at position C in drawing d. The details of B are not shown. Duct A (c) communicates with normal lobules. The width of the connective tissue around the ducts is within normal limits. Two dilated ducts (l and Il), containing protein plugs, are shown at higher magnifications of duct C (d). Note the abnormal width of the fibrous tissue and the irregular caliber of the duct. 944

4 May 1972 THREE-DIMENSIONAL RECONSTRUCTION OF PANCREATIC DUCTS 945 mens stained with periodic acid-schiff indicated to us that mucopolysaccharide cannot usually be found in such specimens. In figure 2 it can be seen that every possible transitional form of protein precipitate may be present. At one extreme (fig. 2, 2) are the mature protein plugs, often calcified; at the other end of the spectrum (fig. 2, 1) are delicate films of protein which may be deposited by the pancreatic juice in entirely normal ducts. Plugs and calculi are invariably situated within the ducts. The ducts themselves are often, but not always, dilated at the level of the plugs. In a few cases, stenosis was present between a plug in a secondary branch and the main duct itself. Generally, however, there was no obstruction to the flow of juice below the plugs. 3. The duct epithelium in contact with a plug or calculus usually shows evidence of damage. Atrophic epithelium adjacent to the plugs tends to disappear entirely at a later stage. Furthermore, this atrophic epithelium tends to desquamate, producing intraluminal deposits of a different type than the protein plugs (fig. 3). Following this loss of the lining epithelium, the lumen of the duct becomes obliterated by the invasion of underlying connective tissue. This obliteration of the lumen extends to a varying degree up the duct and may have several consequences: the formation of a cui de sac from a duct which is already dilated; cords of epithelial cells without lumen may persist; strands of lymphocytes and fibroblasts replace normal tissue between the atrophic area (fig 4); in certain cases, a small cyst is enveloped in the connective tissue between two obliterated segments. D. Involvement of the lobules. The affected lobules give an appearance of having regressed in part or whole to the embryological state of ducts without acini. These ducts have a dilated lumen lined with cuboidal epithelium resembling excretory tissue and sometimes filled with protein precipitates. On the whole, whenever significant dilation is found, the lobule is drained by an occluded duct. Occasionally, however, a normal lobule is seen to drain into a duct dilated above an occlusion. Alternatively, a lobule with several dilated acini may be seen to drain into a completely normal duct system. E. Lesions in advanced stages of the disease. In the advanced stages of this condition, the pancreas is almost entirely replaced by fibrous tissue with atrophy of the lobules and epithelial tis- FIG. 2. Higher magnification of duct B seen in figure 1. A dilated duct is seen to contain a dense protein plug (2). In (1), a protein film is seen which represents the limit of what may be found in normal ducts. FIG. 3. Duct, from another patient, containing desquamated epithelial tissue (a). Cross-hatched area, fibrosis.

5 946 NAKAMURA ET AL. Vol. 62, No.5 FIG. 4. An example of an advanced stage of chronic calcifying pancreatitis from a 3rd patient. The only remains of an interlobular duct is a strand of mononuclear cells. The site of the lobule itself is shown by a collection of mononuclear cells and by groups of acinar cells and ducts, for the most part without a lumen. FIG. 5. Segment of duct and the area it drains from a pancreas showing pancreatitis behind a small carcinoma which blocked the duct of Wirsung. This specimen was obtained from a 4th patient at autopsy. Cross lwtched area, fibrosis; stippled area, lobules in which the normal features are partially or completely preserved. sue. The finer branches of the ducts are affected as often as the larger secondary and tertiary ducts. The lobules and ducts (fig. 4) above the tertiary ducts disappear and are replaced by collections of lymph. ocytes. Normal exocrine tissue is often isolated in fibrous tissue without any com munication with the duct system. Cysts are found where the duct epithelium has desquamated extensively. Paradoxically, the islets of Langerhans survive and look hyperplastic. II. Spatial reconstruction of the ducts in pancreatitis secondary to an obstruc tion in the main pancreatic duct: These lesions are different in almost every reo spect to those described above (fig. 5). A. The lesions are evenly distributed throughout the entire exocrine tissue of the gland. B. The alterations in the ducts are much less striking. For example, the caliber remains regular, without alternat ing stenosis and dilation, while the ducts are only moderately dilated and, indeed, the finer branches maintain a normal diameter. The lining epithelium is intact, the lumen is empty, and only very excep tionally are any protein plugs detectable. C. The appearance of microcystic dila tion of the intralobular ducts is rare.

6 May 1972 THREE-DIMENSIONAL RECONSTRUCTION OF PANCREA TIC DUCTS 947 III. The polyvinyl casts of the ducts. Figure 6 shows a case from a normal pancreas in which the regularity of the branching of the ducts is apparent, and the duct system in the pancreas of a patient with calcifying chronic pancreatitis in which irregular dilation of the duct of Wirsung is present. This dilation is marked in the secondary and tertiary branches also and no finer branches of the ducts can be seen entering the tertiary branches. Discussion Three-dimensional reconstructions of 13 specimens of pancreas have provided confirmation of our notions as to the na- A B FIG. 6. A, polyvinyl cast of the main pancreatic duct and its branches in a normal pancreas. B, polyvinyl cast of the main pancreatic duct and its branches in the pancreas of a patient with calcifying chronic pancreatitis. The cast was made from the tail and part of the body of the gland removed at operation.

7 948 NAKAMURA ET AL. Vol. 62, No.5 ture of the lesions of peep previously obtained from studies of single sections At no stage in the evolution of these lesions did they resemble the changes due to obstruction of the main duct by slowgrowing tumors. The specific characteristics of the lesions of peep are: 1. Spotty distribution of the lesions which appear to be related to changes in the ducts. For this reason, we do not feel that the initial lesion is in the main duct or at the sphincter of Oddi. Further evidence lies in the spatial reconstructions in pancreatitis secondary to an obstruction which show evenly distributed lesions throughout the entire exocrine tissue. 2. Altered structure in ducts of all sizes in which irregularity of caliber, loss of epithelium, and stenosis are present even in the least affected cases, lesions of the ducts being much less marked in advanced cases of pancreatitis secondary to duct obstruction. The observation that the ducts are relatively more affected than the lobules in the early stages of the illness may be missed in single sections. During the course of the disease, an increasing number of ducts become obliterated so that there is an increasing separation of the lobules from the extralobular ducts, which results in atrophy of the exocrine parenchyma. This can also be seen in the casts. Such obliteration has also been shown to be at least partially responsible for the formation of pancreatic cysts. We found many cysts in these specimens, much as in our previous studies. 4 Several different forms of epithelial metaplasia were encountered in the ducts but these were relatively uncommon and bore no relation to the distribution of the lesions. Therefore, they do not appear to play any role in the early evolution of the illness. This finding is opposite to that suggested by Rich and Duff The constancy of intraductal protein plugs is underlined by this study. Although they might be found in pancreatitis secondary to an obstruction of the main pancreatic duct, the great frequency of such plugs is characteristic of peep. The fact that most of them are not stained with periodic acid-schiff indicates that mucoprotein does not play a prominent role in their formation. The fact that all possible transitions exist between the stage where a delicate film of protein is deposited by the pancreatic juice in entirely normal ducts and the stages where mature plugs with concentric laminar concentrations of protein, calcified plugs, and/or calculi are found, suggests to us that these changes are due to the precipitation of pancreatic juice proteins. The biochemical part of this study 6-S has shown that protein precipitate is frequently found in the pancreatic juice collected after surgical operation in patients with peep. This precipitate has the same histochemical features as intraductal protein plugs. Its presence, sometimes provoked by intragastric alcohol instillation, coincides with the random disappearance or diminution in the supernatant of several enzymatic proteins, as estimated by agar gel disc-electrophoresis. The same phenomenon has been observed in the alcoholic rat, where protein precipitation parallels enzyme hyperconcentration in the juice. 9 This strongly suggests that stone formation is the long term consequence of precipitation of pancreatic juice proteins. That protein plugs are frequently observed without any stricture of the pancreatic ducts favors the assumption that they precede the latter. Conclusions Three-dimensional reconstructions of 13 pancreatic ducts showed us that the 10 specimens from patients with alcoholic calcifying chronic pancreatitis had different lesions from those in the specimens from the patients with main duct obstruction or normals. The characteristics found in calcifying chronic pancreatitis are: (1) the lesions are distributed irregularly and are related to the ducts; (2) protein plugs occasionally containing mucoprotein are frequently found in the ducts. These protein plugs evolve into calculi by the deposition of

8 May 1972 THREE-DIMENSIONAL RECONSTRUCTION OF PANCREATIC DUCTS 949 calcium upon their surface; (3) significant lesions may be present in ducts of all sizes. The abnormal ducts may show irregular dilation, loss of duct epithelium, stenosis by invasion of periductal connective tissue into the lumen, cystic distention, or complete loss of acini and ducts in areas where the ducts are blocked. The distribution and evolution of these lesions suggest that precipitation of protein from pancreatic juice is the primary event in this condition. Subsequently, protein plugs and calculi are formed which, in turn, cause the other lesions as a result of increased pressures behind these obstructions. On the contrary, in pancreatitis secondary to an obstruction in the main pancreatic duct, the lesions are different in almost every respect to those described above (fig. 5). (1) The lesions are evenly distributed throughout the entire exocrine tissue of the gland. (2) The alterations in the ducts are much less striking. For example, the caliber remains regular, without alternating stenosis and dilation, while the ducts are only moderately dilated and indeed the finer branches maintain a normal diameter. The lining epithelium is intact, the lumen is empty, and only very exceptionally are any protein plugs detectable. (3) The appearance of microcystic dilation of the intralobular ducts is rare. REFERENCES 1. Sarles H, Sarles JC, Muratore R: Etude anatomique des pancreatites chroniques de l'adulte. Sem Hop Paris 25/5: , Sarles H, Sarles JC, Camatte R, et al: Observations on 205 confirmed cases of acute pancreatitis, recurring pancreatitis and chronic pancreatitis. Gut 6: , Levy VG, Opolon P, Caroli J: Application de la methode de reconstruction aux cirrhoses biliaires. Rev Int HepatoI15: , Sarles H, Sarles JC, Camatte R, et al: Kystes et pseudokystes du pancreas. Vie Med 47: , Rich AR, Duff GL: Experimental and pathological studies on the pathogenesis of acute haemorrhagic pancreatitis. Bull Johns Hopkins Hosp 58: , Figarella C, Marteau C, Sarles H: Etude de sues pancreatiques humains normaux et pathologiques par electrophorese en disque. Eighth International Congress of Gastroenterology, July 7-13, 1968, Prague. Edited by Gregor and Rield. FK Schattauer Verlag. Stuttgart, New-York, 1969, p Ribeiro T, Clemente F, Colomb E, et al: Sue pancreatique humain normal et de pancreatite calcifiante. Recherche d'un mecanisme de precipitation: effet des proteines seriques et presence d'une proteine particuliere dans la pancreatite. Biochim Biophys Acta 251: , Clemente F, Ribeiro T, Figarella C, et al: Albumine, IgG et IgA dans Ie suc pancreatique humain normal chez I'adulte. Clin Chim Acta 33: , Sarles H, Lebreuil G, Tasso F, et al: A comparison of alcoholic pancreatitis in rat and men. Gut 12: , 1971.