PMC4712467_01
Chronological changes seen on CT. a: First examination. The hypo-enhanced mass was 4.2 x 3.9 cm in size with solid and cystic lesions located in the uncus of the pancreas. b: At 21 months after first examination. The tumor shown is 3.9 x 3.6 cm in size. The cystic lesion (yellow arrow) had become smaller and the solid lesion (white arrow) had become larger. c: At 28 months after first examination. The tumor was 4.2 x 3.3 cm in size. The cystic lesion changed and displayed irregular margins
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Fig1
The tumor was demonstrated to be a well demarcated solid and cystic lesion, measuring 4.2 x 3.9 cm in diameter by enhanced CT (Fig. 1a). The size of the pancreatic tumor had become smaller, measuring 3.9 cm in maximum diameter, and the internal structure showed morphological changes with smaller cysts and a larger solid lesion by plain CT (Fig. 1b) and MRI/MRCP (Fig. 2b). MRCP showed an increase in the size and number of the cysts, with no infiltration into the pancreatic ducts (Figs. 1c and 2c).
a, b, c. Chronological changes seen on MRCP. a: At the first examination. The tumor was observed as multiple cystic lesions. b: At 21 months after first examination. c: At 28 months after first examination. Figure 2-d, e, f, g. MRI appearance at 28 months after first examination. d: T1WI. A multi-cystic lesion with low intensity was surrounded by a mass with iso-intensity. e: T2WI. A multi-cystic lesion displays low- to iso-intensity. The surrounding tissue shows iso- to high intensity. f: T2-FAT-SAT. A multi-cystic high intensity lesion is shown. The surrounding tissue shows complete fat suppression. g: T2WI (coronal image). A ringed multi-cystic lesion with high intensity is surrounded by a smooth superficial mass. A small nodule is seen inside of the cyst ring
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Fig2
The main pancreatic duct (MPD) showed no dilation and the evidence of communications between the tumor and MPD was not found (Fig. 2a). MRCP showed an increase in the size and number of the cysts, with no infiltration into the pancreatic ducts (Figs. 1c and 2c). T2-weighted imaging (T2WI) and high intensity on T2-fat saturation (FAT-SAT) by MRI. The solid lesion surrounding the multi cystic lesion displayed iso-intensity on T1WI, iso- to high intensity on T2WI and low intensity with complete fat-tissue suppression using T2-FATSAT conditions (Fig. 2d-f). These findings demonstrated that the cystic lesion consisted with pancreatic juice and the solid lesion was a fat tissue. T2WI imaging, ringed-multilocular cysts with high intensity were surrounded by a smooth superficial mass, and a small nodule was observed inside of the cyst ring (Fig. 2g). These images suggested the possibility of IPMN malignant transformation.
Intraoperative ultrasound examination. A well-demarcated honeycomb-like cystic lesion in the pancreatic uncus was found. There was no evidence of venous or ductal invasion
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Fig3
Intraoperative ultrasound showed a well demarcated honeycomb-like cystic lesion in the pancreatic uncus, and there was no evidence of venous or ductal invasion (Fig. 3).
Macroscopic and pathological findings of the pancreatic hamartoma. a: Solid and cystic tumor in the pancreatic uncus with a smooth, thin capsule. Cysts were surrounded by yellow adipose tissue and a white nodule was found between the cysts. b: The solid lesion filled with mature adipose tissue. There was no evidence of mucinous products in the cysts and no evidence of malignancy in the epithelial cells of the cysts. c: The cystic lesion consisted of dilated ducts. Fibrosis and infiltration of monocytes were observed around the cysts. There were a few normal acini in the solid lesion, and the nodule located between the cysts consisted of stromal fibrosis without atypical cells
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Fig4
The inner structure of the tumor consisted of multiple cysts, and a white nodule was found between the cysts (Fig. 4a). A few normal scattered acini were observed in the solid portion of the lesion, and the nodule located between the cysts consisted of stromal fibrosis without atypical cells (Fig. 4b).
Immunohistochemical stains. The epithelial cells of the ducts expressed cytokeratin 7 and cytokeratin 19, but were negative for cytokeratin 20. The adipose tissue was positive for S-100 protein and mostly negative for MIB-1
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Fig5
These results suggest that the tumor was non-proliferative (Fig. 5).