Acta Pathologica Japonica 1993; 43: 434-439

Case Report A case of AFP-positive pancreas papillary carcinoma suggestive of a primitive endoderm phenotype

Kazuhiro Iwai,l Hiroshi Ishikura,’ Tsuneo lnoue2 and Takashi Yoshiki’

‘Department of Pathology, Hokkaido University School of Medicine, Sapporo and ‘Department of Surgery, Chitose Municipal Hospital, Chitose, Japan

In a 70 year old woman with a tumor in the head of the pancreas, the lesion was predominantly composed of papil- lary adenocarcinoma protruding into the main pancreatic duct, with periductal invasion. The major portion of the adenocarcinoma was intraductal and was composed of tall columnar epithelial cells with pseudostratified nuclei, had the appearance of primitive endodermal epithelium and was positive for carcino-embryonic antigen. In contrast, in the other portion of the adenocarcinoma which had the predomi- nant component of periductal invasion, neoplastic cells had an irregular, eosinophilic cytoplasm, resembled ordinary pancreas adenocarcinoma of ductal origin and was positive for CA19-9. Neuro-endocrine and alpha-fetoprotein-positive cells with a primitive appearance were scattered among the neoplastic epithelial linings. In addition, a vimentin-positive sarcomatoid component intermingled with the adenocarci- noma. These findings suggest that the adenocarcinoma observed in this tumor with the primitive appearance also had a primitive phenotype. This was evidenced by immuno- histochemistry and the divergent directions of differen- tiation. This particular case illustrates that pancreas adenocarcinoma of the ordinary histologic type can arise secondarily from the more primitive neoplastic cells during carcinogenesis within the pancreatic duct.

Key words: alpha-fetoprotein, multipotentiality, neoplasm, pancreas

Pancreas cancer, most of which is of duct cell origin, is an aggressively behaving neoplasm. It has been postulated that the tumorigenesis of most pancreatic adenocarcinoma of duct cell origin is via a dysplasia-adenocarcinoma sequence

Correspondence: Hiroshi Ishikura, MD, Department of Pathology, Hokkaido University School of Medicine, N-15, W-7, Kita-ku, Sapporo 060, Japan.

Received 7 September 1992. Accepted for publication 30 March 1993.

or a de novo generation of adenocarcinoma cells directly from normal duct cells. A tumor of the pancreas with a major portion having a primitive phenotype is described in this study from histopathologic and immunohistochemical aspects. In addition, a histologically different type of adeno- carcinoma was intermingled with the tumor and it had a more ordinary appearing duct cell adenocarcinoma. A transition between the primitive-appearing and ordinary ductal adeno- carinoma cells was evident. The importance of neoplastic ductal cells with a primitive phenotype in the tumorigenesis of the more usual form of aggressive pancreatic cancer must be stressed.

CLINICAL SUMMARY

A 70 year old Japanese woman was admitted to hospital with the chief complaint of jaundice. Ultrasonography and com- puter tomography revealed a mass in the head of the pancre- as and also that the common bile duct was greatly dilated. No other abnormality was found during the clinical proceed- ings. Laboratory data on admission included total bilirubin, 24.7 mg/dL; carcino-embryonic antigen (CEA), 9.1 ng/mL; CA19-9, 2700 U/mL; alpha-fetoprotein (AFP), 10.7 ng/mL and DUPAN-2, 11 00 U/mL. Percutaneous trans-hepatic cholangio- drainage was performed and the jaundice diminished. Pan- creaticoduodenectomy was successful but the patient died 8 months later with multiple liver metastases. Permission for autopsy was not obtained.

PATHOLOGICAL FINDINGS

Gross findings

A 3.5 x 3.0 x 3.0 cm tumor was confined to the head of the pancreas around the main pancreatic duct. The cut surface

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of the tumor was white and there was no apparent invasion no areas with features of yolk sac tumor or hepatoid adeno- into the duodenum or retroperitoneal tissue. The intra- carcinoma. There was no Paneth cell differentiation of neo- pancreatic biliary duct was obstructed by compression of the plastic cells. tumor. Lymph node metastasis was not grossly evident.

Histopathology

The tumor was mainly composed of adenocarcinoma cells with tubule and papillae formation. While the proliferation of adenocarcinoma is usually intraductal and papillary (Fig. 1 ), an invasive growth into the surrounding periductal stroma can also be prominent. The papillary adenocarcinoma appeared to be embryonic because of pseudostratification and hyperchromasia of the nuclei and an occasional clear cytoplasm of neoplastic cells (Fig. 2). In some areas, goblet cells filled with mucin were interspersed. In addition to adenocarcinoma with an embryonic appearance, there were adenocarcinoma cells with an eosinophilic and irregular- shaped cytoplasm (Fig. 3). These cells were often contigu- ous with pseudostratified adenocarcinoma cells with an embryonic appearance, or were invasively dispersed in the periductal connective tissue. These irregular-shaped adeno- carcinoma cells are responsible for stromal invasion as well as for lymphatic vessel permeation, Histologic features of the latter adenocarcinoma cells were identical with the usual pancreatic adenocarcinoma cells of duct origin. There were

Figure 2 Adenocarcinoma portion with embryonic appearance, Nuclear hyperchromasia and pseudostratification are prominent (HE).

Figure 3 Adenocarcinoma cells with an eosinophilic cytoplasm and irregular cytoplasmic contour, distinct from the tall columnar, pseudostratified adenocarcinoma cells with an embryonic appear- ance. These cells are either contiguous with papillarily-proliferating, embryonic adenocarcinoma cells or they have invaded the peritu- bular connective tissue (HE).

Figure 1 proliferate and protrude into the ductal space (HE).

Major tumor mass in the pancreatic duct. Tumor cells

436 K. lwai eta/.

Figure 4 Sarcomatous spindle cells proliferating underneath the lining of adenocarcinoma cells. Osteoclast-like multinuclear cells are absent (HE).

Figure 5 Argyrophilic cells scattered among adenocarcinoma components with an embryonic appearance. The argyrophilic gran- ules are distributed at the basal portion of the neoplastic columnar cells (Grimelius stain).

~ ~ -_____ --*

Figure 6 Different distribution of CEA, CA19-9 and epithelial mem- brane antigens in the adenocarcinoma portion. (a) CEA is demon- strated in embryonic appearing, tall columnar adenocarcinoma cells. (b) CA19-9, in contrast, is positive in adenocarcinoma cells with an irregular contour and an eosinophilic cytoplasm. Epithelial mem- brane antigen (c) and low molecular weight cytokeratin (not shown) are also evident in the CA19-9-positive, irregular contoured adeno- carcinoma portion (SABC method).

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In addition to the adenocarcinoma, the tumor contained a minor component of a sarcomatoid area. These sarcomatoid

an embryonicappearance (Fig. 6a).The distribution of CA19-9 differed from that of CEA. CA19-9 was positive in the adeno-

cells were plump and spindle-shaped and had sparse mitotic figures. No specified differentiation involving chondroblastic, rhabdomyoblastic or osseous features was evident. The sarcomatoid cells did not have features of blastematous cells (Fig. 4). Osteoclast-tumor cells were absent. The sarcoma- toid cells were closely associated with the papillary adeno- carcinoma cells but there was no obvious transition between them. Silver impregnation revealed that in the sarcomatoid portion, reticulin fibers surrounded the individual tumor cells.

Some papillary adenocarcinoma cells with an embryonic appearance were intensely argyrophilic (Fig. 5).

carcinoma of eosinophilic and irregularly shaped cytoplasm, but negative in papillary adenocarcinoma cells which had an embryonic appearance (Fig. 6b). Epithelial membrane anti- gen (EMA) and low molecular weight cytokeratin were posi- tively stained in the adenocarcinomacells in a pattern identical to that seen with CA19-9 (Fig. 6c). Chromogranin-positive and Leu-7-positive cells were present in the adenocarcinoma portion and were predominant along the basal portion of the neoplastic cells (Fig. 7). The distribution of chromogranin and Leu-7 immunoreactivity was virtually identical with that

Table 1 Monoclonal antibodies used in this study

MoAb specificity Antisera specificity lmrnunohistochemistry

Paraffin-embedded blocks were made from 10% buffered CEA Chromogranin formalin-fixed (pH 7.4) material. Four micron-thick sections CA19-9 Pancreatic polypeptide were cut, deparaffinized, and rehydrated. Immunohisto- chemical staining was performed using the streptococcal avidin-biotin-peroxidase complex (SABC) method (Nichirei, Tokyo, Japan). Monoclonal antibodies and their sources are listed in Table 1. Appropriate positive and negative control slides were stained simultaneously in each immunohisto- chemical staining. Non-immune sera gave no positive stain- ings under these conditions.

Carcino-embryonic antigen stained along the luminal and lateral surface of the neoplastic tubules or papillae which had

€MA Gastrin Leu 7 Somatostatin Low molecular cytokeratin Insulin AFP Glucagon

Serotonin Calcitonin Amylase Desmin s-loo

CEA, CA19-9 and EMA sourced from Nichirei, Tokyo, Japan. Leu-7 sourced from Becton Dickinson, San Jose, CA, USA. All other antibodies were sourced from Dakopatts, Glostrup, Denmark.

Figure 7 Neuro-endocrine differentiation of adenocarcinoma cells with an embryonic appearance; immunohistochemical staining for (a) Leu 7 and (b) chromogranin. Both Leu 7 and chromogranin positivity are distributed in the basal portion of the neoplastic cells, the pattern of which is virtually identical with that seen with the Grimelius stain results illustrated in Fig. 4 (SABC method).

438 K. lwai eta/

Figure 8 Alpha fetoprotein-positive cells in the major adenocarci- noma portion (SABC method).

Figure 9 A schematic illustration of histologic patterns and antigenic distribution in the pancreas cancer. The black area (m) represents the papillarily-protruding, CEA/AFP/neuroendocrine marker-positive portion, whereas the grey area (0) shows the peripherally invading, CA19-9/EMA/cytokeratin-positive portion. The papillary area has an embryonic appearance, whereas that invading the peripheral area has an ordinary histology of pancreatic ductal adenocarcinoma. The dotted area (H) represents the sarcomatoid portion. The double arrowheads indicate neural invasion. The finely dotted areas (El) indicate chronic pancreatitis with fibrosis (D, duodenum; M, duo- denal muscular layer; P, intact pancreas; MPD, main pancreatic duct).

of argyrophil cells; they were exclusively present in the papillary adenocarcinoma with an embryonic appearance. Similarly, immunoreactive cells for pancreatic polypeptide, glucagon, insulin and gastrin were scattered with the same distribution seen with Leu-7 and chromogranin, although fewer cells were positive for these antigens. Cells immuno- reactive for somatostatin were the most numerous of the neuroendocrine-type tumor cells. There were no cells immunoreactive for serotonin or calcitonin. Alpha-fetoprotein was demonstrated in some papillary adenocarcinoma cells with an embryonic appearance (Fig. 8). In contrast, a weak staining for vimentin was present exclusively in the sarcoma- toid cells and the adenocarcinoma cells did not stain. There were no amylase-positive cells anywhere in the tumor. Des- min and S-100 protein were also absent in all tumor cells. lmmunohistochemical findings in terms of antigenic distribu- tion and histologic patterns are schematically illustrated in Fig. 9.

DISCUSSION

Carcinoma of the pancreas is predominantly composed of intraductally proliferating, papillary adenocarcinoma cells with an occasional clear cytoplasm. The primitive appearance of this part of the tumor is associated with a primitive phenotype as evidenced by dispersed AFP-positive cells. The associa- tion of AFP-positive cells with the primitive appearance of an adenocarcinoma is also observed in cases of pulmonary blastoma or fetal type adenocarcinoma of the The primitive adenocarcinoma in the current tumor contained abundant neuro-endocrine and goblet cells, although the dispersed neuro-endocrine cells are demonstrated in a rather ordinary type, duct cell adenocarcinoma of the pancreas, thereby never being specific for a primitive phen~type.~ ,~ The presence of small sarcomatoid portions does not mean that the entire tumor is a carcinosarcoma.6-9

An interesting finding in the present tumor was that CA19-9 and CEA antigenic distributions were entirely different. Carcino-embryonic antigen-positive adenocarcinoma cells differed from CA19-9-expressing adenocarcinoma cells in that the latter did not have an embryonic appearance but did have an eosinophilic cytoplasm and an irregular contour. In addition, EMA and cytokeratin were exclusively expressed in the CA19-9-positive adenocarcinoma cells. Therefore, CA19-9-expressing and CEA-expressing adenocarcinoma cells may represent a different functional status, or a different lineage of differentiation. This distinct distribution of CA19-9 and CEA antigens also shows the multipotentiality of the current tumor. In this case, CA19-9/EMA/cytokeratin-positive adenocarcinoma cells may be one of the differentiated com-

Pancreatic carcinoma 439

ponents from the CEA-expressing, embryonic adenocarci- noma cells.

Another type of pancreatic tumor with divergent differ- entiation has been called pancreatoblastoma.’0’2 This tumor occurs in young individuals and produces a relatively large amount of AFP. An acinic cell differentiation in a pan- creatoblastoma is a well-recognized feature. In the current tumor, there was no appreciable acinar cell differentiation. Embryonic-appearing adenocarcinoma is not a predominant feature of pancreatoblastoma, therefore, the current carci- noma differs from a pancreatoblastoma. An AFP-producing acinar cell carcinoma has recently been reported.I3 Again, the absence of acinic cell differentiation distinguishes the current tumor from that reported by Nojima eta/.I3

The irregularly contoured adenocarcinoma cells histo- logically resembled ordinary pancreatic adenocarcinoma cells of ductal origin. The positive staining for CAI 9-9, EMA, and cytokeratin is in accord with their duct cell nature.I4,I5 The aggressive biological behavior of these cells, as charac- terized by stromal invasion as well as lymphatic and blood vessel permeation, supports this notion. It has been pos- tulated that tumorigenesis of most pancreatic adenocarci- noma of duct cell origin is via a dysplasia-adenocarcinoma sequence or de novo generation of adenocarcinoma cells from normal appearing duct cells. From observations of the current tumor it must be emphasized that intraductal neo- plastic cells with the embryonic endoderrnal phenotype may be a progenitor of ordinary pancreas adenocarcinoma of duct origin, probably in a limited number of cases of pan- creas adenocarcinoma. However this hypothesis does not rule out dysplasia-adenocarcinoma or de novo tumorigen- esis of ordinary ductal adenocarcinoma of the pancreas from non-neoplastic ductal epithelial cells.

REFERENCES 1 Barnard WG. Embryoma of lung. Thorax 1951; 7 : 299-301. 2 Spencer H. Pulmonary blastoma. J. Pathol. Bacterial. 1961 ; 82:

1 6 1 - 1 65. 3 Kradin RL, Kirkham SE, Young RH eta/. Pulmonary blastoma

with argyrophil cells and lacking sarcomatous features (pul- monary endoderrnal tumor resembling fetal lung). Am. J . Surg. Patho/. 1982; 6: 165-1 72.

4 Suda K, Hashimoto K. Argyrophil cells in the exocrine pancreas. Acta Pathol. Jpn. 1979; 29: 413-419.

5 Kodama T, Mori W. Morphological behavior of carcinoma of the pancreas: 2. Argyrophil cells and Langerhans’ islets in the carcinomatous tissues. Acta Pathol. Jpn. 1983; 33: 483-493.

6 Alguacil-Garcia A, Weiland LH. The histologic spectrum, prog- nosis, and histogenesis of the sarcomatoid carcinoma of the pancreas. Cancer 1977; 39: 11 81 -1 189.

7 Jefferey I, Crow J, Ellis 8. Osteoclast-type giant cell tumour of the pancreas. J. Ch. Pathol. 1983; 36: 1 165-1 170.

8 Rosai J. Carcinoma of pancreas simulating giant cell tumor of bone: Electron-microscopic evidence of its acinar cell origin. Cancer 1968; 22: 333-344.

9 Tschang TP, Garza-Garza R, Kissane JM. Pleomorphic car- cinoma of the pancreas: An analysis of 15 cases. Cancer 1977;

10 Kakudo K, Sakurai M, Miyaji T et a/. Pancreatic carcinoma in infancy. Acta Pathol. Jpn. 1976; 26: 719-726.

1 1 Horie A, Yano Y, Katoo Y, Miwa A. Morphogenesis of pancreato- blastoma, infantile Carcinoma of the pancreas. Cancer 1977; 39:

12 Cubilla AL, Fitzgerald PJ. Pancreaticoblastoma. In: Cubilla AL, Fitzgerald, eds. Tumors of the Exocrine Pancreas. Armed Forces Institute of Pathology, Washington, 1984; 195-1 99.

13 Nojima T, Kojima T, Kato H, Sat0 T, Koito K, Nagashima K. Alpha-fetoprotein-producing acinar cell carcinoma of the pan- creas. Hum. Pathoi. 1992; 23: 828-830.

14 Cordell J, Richardson TC, Pulford KAF et a/. Production of monoclonal antibodies against human epithelial membrane antigen for use in diagnostic immunocytochemistry. 5r . J. Cancer 1985; 52: 347-354.

15 Moll R, Franke WW, Schiller DL. The catalog of human cytokera- tins: Patterns of expression in normal epithelia, tumors and cultured cells. Cell 1982: 31: 1 1-24.

39: 21 14-21 26.

247-254.

ACKNOWLEDGEMENTS

The authors thank K. Kawai for technical assistance and M. Ohara for reading the manuscript.