PMC7644490_01
Initial CT images showing a 40-mm multilocular cyst on the pancreatic tail. A) Unenhanced CT image showing a multilocular cyst on the pancreatic tail. B) Arterial-phase CT image showing a multilocular cyst with no enhancement. C, D) Venous-phase CT image showing a multilocular cyst with slight contrast enhancement of the cyst septa.
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The cysts were adjacent to each other in a "cyst by cyst" manner, so it was diagnosed as an intraductal papillary mucinous neoplasm (IPMN) and followed (Fig. 1).
CT image after 1 year and 7 months showing peri-cystic fat stranding (arrow).
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One year and 7 months after the initial diagnosis, cyst infection was suspected due to the presence of abdominal pain and peri-cystic fat stranding on CT (Fig. 2).
MRI scan acquired before surgery. Nodules showing a low intensity on both T1WI and T2WI and a high intensity on DWI (arrow). DWI: diffusion weighted imaging, MRCP: magnetic resonance cholangiopancreatography
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The nodules showed a low intensity on both T1- and T2-weighted magnetic resonance imaging (MRI) images and high intensity on diffusion-weighted imaging (DWI) (Fig. 3).
Contrast-enhanced ultrasonography performed before surgery. The nodule is located in the cyst and shows enhancement.
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A 13-mm nodule was found inside the cyst by contrast-enhanced abdominal ultrasonography (Fig. 4).
Transitive graph of the amylase (AMY), CRP and CA19-9 levels. CRP: C-reactive protein, CA19-9: carbohydrate antigen 19-9
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Furthermore, the level of carbohydrate antigen (CA) 19-9 had also increased over time, and malignancy could not be ruled out (Fig. 5).
Pathological findings. (A) The resected pancreas cyst revealed a papillary and whitish nodule inside (arrow). (B, C) Microscopically, the cyst had relatively thick fibrous wall and a nodule inside (B: original magnification x12.5, C: Loupe image). (D) A closer view showed a papillary-growing tumor inside the cyst (original magnification x100). (E, F) Invasive tubular adenocarcinoma was associated with MCN (arrowheads) (E: original magnification x12.5, F: original magnification x100). B-F: Hematoxylin and Eosin staining. MCN: mucinous cystic neoplasm
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A macroscopic examination of the surgical specimen revealed a 32x28-mm cyst containing a papillary nodule (Fig. 6A). Microscopically, the cyst had thick fibrous wall and a papillary-growing tumor inside (Fig. 6B). The tumor cells exhibited eosinophilic cytoplasm with irregularly spaced, enlarged and roundish nuclei (Fig. 6D). The tumor invasion was observed as tubular adenocarcinoma (Fig. 6E, F).
Ovarian-like stroma. Spindle-shaped stromal cells were seen at the cyst wall and septum (A) and were immunohistochemically positive for SMA (B), ER (C) and PgR (D). A: Hematoxylin and Eosin staining, B: immunohistochemistry for SMA, C: immunohistochemistry for ER, D: immunohistochemistry for PgR (A-D: original magnification, x100). SMA: smooth muscle actin, ER: estrogen receptor, PgR: progesterone receptor
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The cyst wall contained abundant spindle-shaped stromal cells growing in fascicles, which were immunohistochemically positive for ER, PgR and smooth muscle actin (SMA), suggesting that they were ovarian-like stroma (Fig. 7).