Radical resection of T1 pancreatic adenocarcinoma with a pseudocyst of the tail due to acute obstructive pancreatitis: report of a case
© The Author(s). 2016
Received: 2 November 2016
Accepted: 17 November 2016
Published: 30 November 2016
A 53-year-old male visited his primary physician for epigastric and back pain. Abdominal-enhanced computed tomography (CT) revealed a simple cyst of the pancreatic tail attached to the stomach. A distal main pancreatic duct (MPD) was clearly dilated, but no pancreatic tumor was identified around the stenosis of MPD by CT scan and magnetic resonance cholangiopancreatography (MRCP). Endoscopic retrograde pancreatography (ERP) revealed stenosis and distal dilation of the MPD located between the body and tail of the pancreas. Endoscopic ultrasound (EUS) revealed a low density mass of 7 mm in size with distal dilation of the MPD. With the suspicion of a small pancreatic cancer, the patient underwent distal pancreatectomy and splenectomy with lymph node dissection (D2). On histopathological evaluation, a small pancreatic adenocarcinoma of 6 mm in size was detected around the stenosis of MPD. Final pathological diagnosis was moderately differentiated invasive ductal adenocarcinoma of the pancreas with no lymph node metastasis (Japan Pancreatic Society (JPS) classification 7th edition; Pbt, TS1 (6 mm), tub2, intermediate type, INF β, ly1, v1, ne1, mpd(-), pT1b, pN0, pM0, stage IA,PCM(-), DCM(-) and the Union International Control Cancer (UICC) classification of malignant tumors 6th edition; pT1, pN0, pM0, stage IA, R0). We herein reported a patient who underwent radical resection for T1 pancreatic adenocarcinoma of 6 mm in diameter which caused acute pancreatitis and a pseudocyst due to obstruction of the MPD.
Pancreatic cancer is one of the most frequent malignant tumors in the world. An overall survival rate remains poor because of advanced stage at the time of diagnosis, and rapid tumor growth despite the improvement in imaging studies . Surgical cases of tumor factor 1 (T1) in patients with pancreatic cancer are rare which are 2.95% in the literature, of which the tumors less than 10 mm in size account for only 0.55% in patients with resectable pancreatic cancer . We herein reported a radical resection of patients with a 6 mm T1 pancreatic adenocarcinoma which prevented clinically as a pseudocyst due to obstructive acute pancreatitis.
On histopathological evaluation, the small pancreatic adenocarcinoma of 6 mm in size was detected near the stenotic MPD. The obvious cancer cell invasion around the tumor was not detected but an invasion to the small veins (v1) and lymphatic ducts (ly1) as well as small neural infiltration (ne1) were present. Final pathological staging was moderately differentiated invasive ductal adenocarcinoma of the pancreas with no lymph node metastasis (Japan Pancreatic Society (JPS) classification 7th edition; Pbt, TS1 (6 mm), tub2, intermediate type, INF β, ly1, v1, ne1, mpd(-), pT1b, pN0, pM0, stage IA,PCM(-), DCM(-) and the Union International Control Cancer (UICC) classification of malignant tumors 6th edition; pT1, pN0, pM0, stage IA, R0). The resection margins were fine of cancer involvement. The patient developed surgical site infection and chylous ascites, and the patient was discharged on postoperative day 53. The patient will receive an adjuvant chemotherapy with TS-1 for 6 months.
Previously, a small tumor (<2 cm in diameter) was a good prognotic factor in patients with pancreatic cancer for the first time in 1964 . Therefore, the tumor size (TS) was categorized by the criteria of the JPS as TS1, <2 cm; TS2, 2.1–4.0 cm; TS3, 4.1–6.0; or TS4, >6.0 cm. However, the rates of T1 and stage I in the JPS classification in all patients with TS1 pancreatic cancer were only 21.6 and 14.9%, respectively, because of locally advanced tumor invasion. Moreover, the rate of lymph node metastases was 46.1% in patients with TS1 pancreatic cancer . Therefore, the TS may not reflect prognosis in patients with pancreatic cancer. Other investigators suggested that the small pancreatic ductal adenocarcinoma (<1.0 cm in diameter) or carcinoma in situ was a good postoperative prognosis, thus categorized as early pancreatic cancers . The rates of early pancreatic cancer, TS1 pancreatic cancer, or stage I pancreatic cancer in patients with all resectable pancreatic cancers were 0.55, 4.05, or 27%, respectively . However, a significant difference of prognosis between an early pancreatic cancer and other stage I pancreatic cancers with a tumor diameter of 1–2 cm had not been reported because of the small numbers of patients.
Tumor markers such as CEA and CA19-9 are very useful tools to screen for detection and recurrences of malignant diseases. Although about 80% of patients with pancreatic cancer are positive for serum CA19-9, mostly in advanced stages, false-positive rates are very high (20–30%) in patients with beginning hepatobiliary-pancreatic diseases . The estimation of CEA and CA19-9 may not be useful to diagnosis as pancreatic cancer at an early stage. However, in the current case, the preoperative serum CEA was slightly increased. After distal pancreatectomy, serum CEA decreased to normal limits. In this case, the reason of preoperative elevation with serum CEA seemed to be caused by the pancreatic pseudocyst of the tail.
The microscopic invasion of the lymph ducts and vessels in patients with pancreatic cancer is associated with significantly poor prognosis because of high T stage, absent lymph node metastasis, and perineural invasion . However, a significance of microscopic invasion of the lymph ducts and vessels in patients with pancreatic cancer in stage I remains unclear.
The diagnosis of early pancreatic tumor is still difficult despite the development of CT, MRI, and endoscopic ultrasound (EUS). MRI offers several benefits for imaging of the pancreas. In particular, MRCP obtained with long echo times on T2-weighted MR images may help to demonstrate the pancreatic ductal systems and detect small pancreatic tumors. However, the differentiation between small pancreatic cancer and pancreatitis is still difficult on T1-weighted and T2-weighted MR images . The preoperative indication of ERCP except for a biliary drainage has been declining because of the development of MRCP. However, ERCP seems a very useful examination to detect stenosis of the MPD in patients with small pancreatic cancer combined with inflammation as compared with MRCP . In the current case, ERCP clearly detected the local stenosis of the MPD and the normal smooth MPD of the pancreatic head which suggested the negative suspicion of a pancreatitis. Therefore, diagnostic ERCP seems still valuable if a tumor is suspected despite the negative results on other images or differentiation between inflammation and cancer. EUS is reported to be superior to CT, MRI, and PET in the detection of small tumors in the pancreas and lymph node metastases as well as invasion of the major artery . The typical features of pancreatic cancer was seen by EUS as a hypoechoic mass with irregular borders compared with normal pancreatic tissue. EUS-guided fine needle aspiration (EUS-FNA) is also a safe and highly accurate method for a pathological diagnosis of a tumor. However, the disadvantage of EUS as well as EUS-FNA is that the accuracy and sensitivity of these examinations depend on the technique of the operators. As a result, to detect small pancreatic tumors and for differential diagnosis of pancreatic cancer and pancreatitis, we need to consider the advantage and disadvantage of each image modality.
Nakamura T et al.  was reported to perform pancreaticoduodenectomy in patients with pancreatic cancer less than 1 cm in a diameter. The case was not any symptoms but incidentally serum CA19-9 elevation. To our knowledge, this is the first resectable case of such a small pancreatic cancer less than 1 cm in a diameter with complication of acute pancreatitis and formation of a pseudocyst due to obstruction of the MPD.
YFuj carried out the acquisition of the data and drafted the manuscript. SF, KM, and YFut were involved in the drafting of the manuscript. OY revised the manuscript. KY was the chief supervisor. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.
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