PMC9326047_01
Abdominal ultrasonography shows a well-defined, irregular-shaped, heterogeneous mass at the pancreatic tail (A). The main pancreatic duct was dilated with hyperechoic structures inside (arrowheads) (B).
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F1
Abdominal ultrasonography showed a well-defined, irregular-shaped, heterogeneous mass at the pancreatic tail (Figure 1A). The MPD was dilated with hyperechoic structures (Figure 1B).
Dynamic contrast-enhanced computed tomography shows that the pancreatic tail mass has solid and cystic components. The solid components of the lesion showed hypo-enhancement, whereas the cystic components of the lesion showed non-enhancement during all phases (A) arterial phase, (B) portal phase, (C) equilibrium phase).
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F2
The solid components of the lesion showed hypo-enhancement, whereas the cystic components of the lesion showed non-enhancement during all phases (Figures 2A-C).
Magnetic resonance T1-weighted image (A), T2-weighted image (B), diffusion-weighted image (C), and apparent diffusion coefficient map (D). T2-weighted images show a heterogeneous and hyperintense mass in the pancreatic tail (B). The area corresponding to solid components on computed tomography shows hyperintensity on diffusion-weighted images with a b factor of 800 s/mm2 and hypointensity on the apparent diffusion coefficient map (C,D). The signal intensity of the main pancreatic duct in the tail was high on T1-weighted image and low on the T2-weighted image (arrowheads).
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T2-weighted images showed a heterogeneous and hyperintense mass in the pancreatic tail (Figure 3B). The area corresponding to the solid component seen on CT showed hyperintensity on diffusion-weighted images with b factor of 800 s/mm2 and hypointensity on the apparent diffusion coefficient map, indicating diffusion restriction (Figures 3C,D). T1-weighted image and low on the T2-weighted image (Figures 3A,B), suggesting the presence of a highly viscous substance like mucin within the MPD. The correlation between the cystic components of the lesion and MPD was suggested but not confirmed following
Contrast-enhanced harmonic endoscopic ultrasonography shows mixed hypo-/non-enhancement patterns in the pancreatic tail mass solid components.
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CT and MRI. The MRI signal pattern of peritoneal and omental nodules was similar to the solid component of the pancreatic mass. Contrast-enhanced harmonic EUS (CH-EUS), the solid component of the pancreatic tail tumor, showed mixed hypo- and non-enhancement patterns (Figure 4).
On endoscopic retrograde cholangiopancreatography (ERCP), the papillae shows a fish-mouth appearance (A). After ERCP catheter insertion into the main pancreatic duct, extrusion of mucus from the pancreatic orifice of the papillae was observed (B). Contrast injection shows the correlation between the main pancreatic duct and the mass at the pancreatic tail (C). Per-oral pancreatoscopy showing an irregular-shaped solid mass in the pancreatic tail (D).
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The ampullary orifice was dilated to the so-called fish-mouth appearance (Figure 5A). After ERCP catheter insertion into the MPD, extrusion of highly viscous mucus from the pancreatic orifice of the ampulla was observed (Figure 5B). Contrast injection during ERCP confirmed the correlation between the MPD and the mass at the pancreatic tail (Figure 5C). POPS revealed an irregular-shaped solid mass in the pancreatic tail after the removal of the abundant and highly viscous mucin (Figure 5D).
Pathological analysis of the pancreatic tissues obtained by biopsy with per-oral pancreatoscopy. Hematoxylin and eosin staining show a marked proliferation of small round atypical cells with hyperchromatic nuclei and scanty cytoplasm (A). Immunohistochemical analysis shows tumor cells positive for synaptophysin (B) and CD56 (C). Tumor cells demonstrate a Ki-67 labeling index of 90% (D).
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Histopathological examination of the biopsied material with hematoxylin and eosin staining showed a marked proliferation of small round atypical cells with hyperchromatic nuclei and scanty cytoplasm (Figure 6A). Immunohistochemical analysis showed that the constituent cells were positive for synaptophysin (Figure 6B), chromogranin A, and CD56 (Figure 6C) and negative for leukocyte common antigen, MUC1, MUC2, and MUC5AC. They had a Ki-67 labeling index of 90% (Figure 6D).