ACCESSORY PANCREATIC TISSUE REPORT OF TWO CASES E. J. HORGAN, M.D., M.S. in Surgery ROCHESTER, MINN. The occurrence of accessory pancreatic tissue in man is rather 1 uncommon; a careful review of the literature by Warthin in 1904 revealed only forty-seven cases, to which he added two. One case was reported in 1894 by Biggs,2 which was not included in Warthin's survey, since which thirty-one additional cases have been reported (Table 1). Twelve of these thirty-two cases were found at operation, the remainder at necropsy. In a series of 321 consecutive necropsies in the Mayo Clinic in which the entire length of the intestine was opened in 314 cases, I found accessory pancreases in two cases (0.6 per cent.). In one case the aberrant tissue was in the stomach; in the other, in the duodenum. These statistics conform to Opie's,3 who found ten cases of aberrant pancreatic tissue in 1,800 necropsies. In several instances, I have observed accessory pancreatic tissue in the jejunum at operation. In one instance, it was about 3 inches from the ligament of Treitz opposite the mesentery, and it was necessary to go below it in order to perform a gastro-enterostomy. A macroscopic and microscopic study of the two specimens of accessory pancreatic tissue that I found at necropsy forms the basis of this investigation. I have, in addition, reviewed the embryology of the pancreas in an effort to ascertain the cause of abnormally situated masses of pancreatic tissue. SPECIMENS OF ACCESSORY PANCREATIC TISSUE Case 1 (139972).—At necropsy on a woman, aged 64, a small tumor was found in the duodenum, 5.5 cm. below the pylorus and 3 cm. above the papilla of the common bile duct. The base of the tumor was 1.5 cm. by 1.5 cm., and it projected 1 cm. into the lumen of the bowel (Fig. 1). Microscopic examination disclosed it to be an aberrant mass of pancreatic tissue. All the histologie structures of the pancreas were present, namely, ducts, acini, islets and con¬ nective tissue. The growth was covered by the mucous membrane of the duodenum and appeared to be embedded in the submucosa. From the Section on Surgery, Mayo Clinic. 1. Warthin, A. S.: Two Cases of Accessory Pancreas (Omentum and Stomach), Physician & Surg. 26:337-340, 1904. 2. Biggs, G. P.: Supernumerary Pancreas in the Pylorus, Proc. New York Path. Soc. 1894, pp. 55-56. 3. Opie, E. L.: Disease of the Pancreas, Its Cause and Nature, Ed. 2, Philadelphia, J. B. Lippincott Company, 1910. Downloaded From: http://archsurg.jamanetwork.com/ by a University of British Columbia Library User on 06/19/2015 Case 2 (130601).—At necropsy on a woman, aged 21, on the posterior wall of the stomach near the greater curvature, in the prepyloric region, a hemis¬ pherical tumor mass was found, with its rounded surface covered by mucous membrane, projecting into the lumen of the stomach (Figs. 2 and 3). The base was 3 cm. by 2.5 cm., the thickness 1.2 cm. On section, the cut surface of the tumor was pinkish-white with many small lobules. A rich blood supply was manifested by several large blood vessels. The tumor had the appear¬ ance of pancreatic tissue. Microscopic study verified the macroscopic diag¬ nosis by the finding of pancreatic acini, ducts, islets, and connective tissue in about the same relation as in the normal pancreas. Its bases rested on the submucosa and its rounded surface was covered over by the muscularis mucosae and mucous membrane. HISTOLOGIC APPEARANCE OF THE SPECIMENS In both specimens, all the histologie units of the pancreas were identified under the microscope, namely, ducts, acini, islets, and connective tissue (Figs. 4, 5, and 6). In Specimen 1, all the microscopic sections examined showed an increase in the interlobular, interacinar and periductal connective tissue. In Specimen 2, all the sections presented the well known microscopic picture of the normal adult pancreas. Ducts.—Each specimen contained one large duct, which was patent, lined with high columnar epithelium, with an outer coat of dense fibrous tissue, and which I believed to be the main excretory duct. Into this outer coat the inter¬ lobular ducts passed obliquely as they do in the normal gland, an observation which I had made previously.4 Acini.—The arrangement of the cells forming the acini was the same as in the normal pancreas. These large secreting cells are pyramidal in shape and resemble the normal acini cells. The so-called centro-acinar cells were present. Islets.—In Specimen 1, the islets were small and few in number, and there was a moderate fibrosis. In Specimen 2, the islets were numerous. They were normal in size and the cells resembled those of the normal islet. In order to determine whether the acinic cells in the alveoli had been functioning, and if so to demonstrate their activity of function, sections were stained for zymogen. Sections from both specimens were found on microscopic examination to contain large zymogen granules in the cytoplasm of the apical portion of the acinic cells (Fig. 7). The presence of zymogen granules in the acinic cells and a patent excretory duct are sufficient evidence to prove that these tissues were producing pan¬ creatic juice; and by the presence of the islets, one is justified in concluding that they were producing a hormone, which was the same as the internal secre¬ tion from the islets in the pancreas. These observations make it reasonable to assume that aberrant masses of pancreatic tissue are capable of the same function as the normally placed gland and that they function independently of it. EMBRYOLOGY A careful study of the embryology of the pancreas in the minute r' human embryo has been possible only in a few instances, and most of 4. Horgan. E. J.: The Histogenesis of Carcinoma in the Islets of the Pancreas. J. Lab. & Clin. M. 5:429-442 (April) 1920. 5. Lewis, F. T.: Development of the Pancreas, in Keibel, F., and Mall, F. P.: Manual of Human Embryology, Philadelphia, J. B. Lippincott Company, 1912 2:429-445. Downloaded From: http://archsurg.jamanetwork.com/ by a University of British Columbia Library User on 06/19/2015 Fig. 1 (A129972).—Accessory pancreas in the duodenum 5.5 cm. below the pylorus (Probe point may be seen projecting through ampulla of common bile duct). Downloaded From: http://archsurg.jamanetwork.com/ by a University of British Columbia Library User on 06/19/2015 the data are from the study of the development of the pancreas in the lower vertebrates. For this reason and because an accessory pancreas in the dog has been reported by Mann," I reviewed the comparative anatomy and embryology of the pancreas. Comparative Anatomy and Embryology.—From the researches of Oppel 7 and a complete survey of the literature which was compiled and reviewed by him, we have recorded data to prove the occurrence of the pancreas in the vertebrata from the cyclostomes, the lowest form of fish, through the orders of fishes, amphibians, reptiles, birds and mammals, to man. For a long time it was believed that the pancreas was missing in fishes and amphibians, but the organ has been found in many species Fig. 2 (A130601).—Accessory pancreas in the posterior wall, near the greater curvature, in the prepyloric region of the stomach. of these two orders. Oppel believes it could be found in every species of vertebrate if the investigator would make an earnest search for it. It is of interest to know that even though Oppel made serial cross sections of the entire animal he could not demonstrate a pancreas in Amphioxus lanceolatus, the animal which is the only species representing the order of acranial vertebrates and spanning the gap between the ver¬ tebrates and the invertebrates. Other organs are missing in this animal and the pancreas may be. Oppel leaves it an open question. 6. Mann, F. C.: Accessory Pancreas in the Dog, Anat. Record 19:263\x=req-\ 268, 1920. 7. Oppel, A.: Lehrbuch der vergleichenden mikroskopischen Anatomie der Wirbeltiere. Jena, Fischer, 1900. 3:742-870. Downloaded From: http://archsurg.jamanetwork.com/ by a University of British Columbia Library User on 06/19/2015 No doubt the extreme variation in the form of the pancreas in differ¬ ent species of animals has been the cause of its being overlooked by some investigators, for there is no regularity of form for each order of ver¬ tebrates. Oppel and others have found that the gland may exist in the form of (1) single or multiple masses of gland tissue embedded between the muscularis and serosa in the wall of the stomach or duodenum, or both, and having one or more short or long ducts from each mass; (2) one or several gland masses spread out between the layers of the mesen¬ tery and attached to the stomach, duodenum, or intestine and emptying through one main excretory duct from each mass; (3) numerous small or very small glands in fine cordons dispersed throughout the entire Fig. 3 (A130601).—Cut surface of bisected accessory pancreas in the wall of the stomach showing lobules and blood vessels. cavity between the layers of the mesentery, or, (4) numerous small or very small glands growing along the blood vessels, enveloping them like a sheath, and advancing with the blood vessels into the liver and spleen, interweaving the liver as it follows the vessels in their various direc¬ tions, or into the spleen by entering at the hilum with the blood vessels, or spreading over the splenic capsule from the hilum.