Pancreatic vascular malformation was first reported in 1968 by Halpern et al. [1]. Though it is a benign disease, it is clinically important because it can cause epigastric pain, pancreatitis, portal vein hypertension, bleeding, and rupture [2]. However, pancreatic vascular malformation is a rare disease [3] despite the advancement of various imaging modalities [4]. Moreover, most of the pancreatic vascular malformations are arteriovenous malformations (AVMs), with the other types of malformations being rare. The current report describes a patient with capillary lymphatic malformation (CLM) in the pancreatic uncinate process, which was completely resected through a partial pancreatectomy.
Case presentation
A 74-year-old woman, who presented with complaints of repeated upper abdominal pain for 3 days, was admitted to our hospital. She had no relevant past medical history. Abdominal ultrasonography and computed tomography (CT) scan at another hospital revealed a tumor in the pancreatic uncinate process; thus, she was referred to our hospital for a comprehensive examination.
The results of the laboratory tests were found to be almost normal (the italicized text indicates the test results with abnormal values): white blood cell 9130/μl, total bilirubin 1.0 mg/dl, aspartate aminotransferase 16 U/l, alanine aminotransferase 9 U/l, hemoglobin A1c 6.0%, amylase 76 U/l, C-reactive protein < 0.02 mg/dl, Ca 10.3 mg/dl, soluble interleukin-2 receptor 271.0 U/ml, IgG4 31.5 mg/dl, and antinuclear antibody 160 index. The levels of tumor markers were also normal: carcinoembryonic antigen 3.0 ng/mL, carbohydrate antigen 19-9 11.0 U/ml, DUPAN-2 < 25 U/ml, span-1 8.9 U/ml, and elastase-1 85 ng/dl.
An abdominal contrast-enhanced dynamic CT scan showed a 60-mm-diameter tumor in the pancreatic uncinate process, accompanied by multiple cysts (Fig. 1), and the tumor size tended to increase over time. The gastroduodenal artery was noted to be passing through within the tumor. The pancreatic duct was not enlarged and separated from the tumor. The tumor had a poor contrast effect in the arterial phase and a small contrast effect in the equilibrium phase.
The gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (MRI) showed a lobulated tumor with mixed high and low signals on T2-weighted imaging (Fig. 2a). Out-of-phase T1-weighted imaging showed a low-intensity area, which was a fat component. This finding suggested that the tumor was unlikely to be a malignant tumor. However, diffusion-weighted images revealed a high signal lobulated tumor and suggested potential for malignancy (Fig. 2b). Magnetic resonance cholangiopancreatography revealed a soft tissue tumor close to the pancreatic uncinate process, and it was not continuous with the main pancreatic duct.
An upper gastrointestinal examination revealed that the gastric angle was pushed to the dorsal side of the stomach by the tumor. Endoscopic ultrasonography (EUS) showed a collective cystic lesion on the ventral side of the pancreatic uncinate process (Fig. 3). The main pancreatic duct was negative for intraductal papillary mucinous neoplasm. In addition, given that the tumor was accompanied by a cystic lesion, a fine-needle aspiration was not performed.
In the positron emission tomography CT scan, there was no significant fluoro-deoxy-glucose accumulation in the soft tissues of the pancreatic uncinate process.
The tumor in the pancreatic uncinate process was thought to be the possible cause of the upper abdominal pain. Based on the abovementioned findings, we considered that the tumor was a benign vascular malformation, but because the tumor size tended to increase over time, there was a possibility of it being a malignant tumor; thus, we planned on performing a pancreatoduodenectomy (PD).
After a detailed examination, we performed an elective open laparotomy. During the operation, intraoperative findings revealed that the tumor appeared to be benign and was separate from the pancreatic duct or bile duct. We therefore performed a partial pancreatectomy instead of PD. Since the right gastroduodenal artery and small vein penetrated the tumor, they were ligated and detached. The tumor was excised with a small part of the pancreatic uncinate process, and the mesentery of the transverse colon was also removed. The operation time was 200 min with 75 ml blood loss. The patient’s postoperative course was uneventful, and she was discharged on postoperative day 12.
Macroscopically, the tumor was a 58 × 46 × 30-mm specimen with a spongioid appearance of the cut surface (Fig. 4). Histologically, hematoxylin and eosin staining showed a mixed shape of small veins, small arteries, and capillaries (Fig. 5). The pancreatic tissue was recognized within the tumor, suggesting that the tumor originated from the pancreas. There was no lesion with suspected malignancy. We performed immunostaining for CD31, CD34, Factor VIII, and D2-40, which revealed the following in general: CD31 was positive for vascular endothelium and histiocyte; CD34 and Factor VIII were positive for vascular endothelium; and D2-40 was positive for lymphatic endothelium. In the Elastica van Gieson staining, most vessels of the tumor had no muscular layer. These vessels were capillary blood vessels (CD31, CD34, and Factor VIII were positive, and D2-40 was negative) and lymphatic vessels (CD31 and D2-40 were positive; CD34 and Factor VIII were negative). Based on both histological appearance and immunostaining findings, we diagnosed the tumor as a capillary lymphatic malformation (CLM) according to the International Society for the Study of Vascular Anomalies (ISSVA) classification.
