V

Fig. 5. Histology of the distended glands. The distended glands with intrapapillary adenomyomatous hyperplasia consisted of larger or hyperplastic and dilatated glands (a), were weakly immunostained for CA19-9 (arrows) (b) and showed high proliferation activity (arrows) (c). a HE. X50. b Immunostaining for CA19-9. X80. c Immunostaining for Ki67. X80. (Reproduced with permission from [7].)

Table l. Distended glands, or overreplacement, of ampullary mucosa

Source Cases Distended glands Normal

Pancreatoduodenectomy 29 17 12

Autopsy (infants) 18 4 14

Autopsy (adults) 26 20 6

distended glands or 'adenomatoid hyperplasia' of the ampullary mucosa only grow on the extension of the Oddi's sphincter muscle [7].

Immunohistochemically, the distended glands are negative or weakly positive for CA19-9, while the intrapapillary mucosa and valvules are positive, as shown in figure 5b and table 1. According to Sonoue [8] et al., the distended

Fig. 6. Schematic drawing of the overreplacement of the ampullary mucosa. The mus-cularis mucosae of the duodenum (mm) and Oddi's sphincter muscle (Osm) normally merge at the edge of the papilla (a), while in the case of overreplacement, the muscularis mucosae is in contact with a side of the Oddi's sphincter muscle, resulting in distended glands or so-called overreplacement (arrows) (b). CBD = Common bile duct; MPD = main pancreatic duct. (Reproduced with permission from [7].)

Fig. 6. Schematic drawing of the overreplacement of the ampullary mucosa. The mus-cularis mucosae of the duodenum (mm) and Oddi's sphincter muscle (Osm) normally merge at the edge of the papilla (a), while in the case of overreplacement, the muscularis mucosae is in contact with a side of the Oddi's sphincter muscle, resulting in distended glands or so-called overreplacement (arrows) (b). CBD = Common bile duct; MPD = main pancreatic duct. (Reproduced with permission from [7].)

glands can be immunostained with cytokeratin 7 and MUC5AC, markers of pancreaticobiliary phenotype and gastric surface mucin, respectively (fig. 7). Hence, such glands maintain the pancreaticobiliary phenotype, although they are situated on inside or toward the duodenal lumen, and acquire a selectively gastric surface phenotype. The average Ki67LI of the distended glands is 19.6 ± 21.0%, while it is 9.0 ± 11.0% in the intrapapillary glands, a difference which is not significant (p = 0.064) as shown in table 2. However, in 2 cases the distended glands showed a high proliferation index (fig. 5c) and were identified with adenomatous or adenoma-like structures admixed with or without similar proliferation in the tips of the valvules.

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