Characteristic clinical and pathologic features for preoperative diagnosed groove pancreatitis

Groove pancreatitis is a specific form of chronic pancreatitis that extends into the anatomical area between the pancreatic head, the duodenum, and the common bile duct, which is referred to as the groove areas. In 1973, groove pancreatitis was first used to describe segmental pancreatitis of the groove area [1].

Groove pancreatitis is not common, and only three cases have been published in Korea [2-4]. Because of its rarity, the distinct incidence of groove pancreatitis is unknown, but it accounts for 19.5 to 24.4% of pancreaticoduodenectomy performed to treat chronic pancreatitis [1, 5]. Most patients with groove pancreatitis are 40 to 50-year-old males with a history of alcohol abuse [1, 5]. The pathogenesis is still unclear but anatomical and functional obstruction of the minor papilla is one of the issues considered.

We present a series of symptomatic patients with groove pancreatitis who underwent pancreaticoduodenectomy, and review the diagnostic imaging modalities, pathological features and clinical outcomes.

Patients undergoing pancreaticoduodenectomy due to a clinical diagnosis of symptomatic groove pancreatitis supported by radiological imaging that included computed tomography (CT), endoscopic ultrasonography (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) were retrospectively included in the study from May 2006 to May 2009. Groove pancreatitis was confirmed histologically in 5 patients, and the final diagnosis of one patient was distal common bile duct cancer. Collected data included demography, clinical presentation, diagnostic imaging work-up, histologic results and clinical outcomes.

The pathogenesis of groove pancreatitis remains unclear. Anatomical or functional obstruction of the minor papilla is one of the issues considered. It is explained that Brunner gland hyperplasia and stasis of pancreatic juice in the dorsal pancreas leads to pancreatitis in the groove area [1]. And anatomical factors, including a duodenal bud and ectopic pancreas, are other possible reasons for groove pancreatitis [6]. We experienced six patients diagnosed with groove pancreatitis by clinical diagnostic modalities and pathologic examination. Ectopic pancreas in groove area was suspected by EUS but was not confirmed by pathology.

In 3 of the 5 cases (60%), cystic changes in the duodenal wall including one pseudocyst were detected. Thickening and scarring of the duodenal wall close to the minor papilla usually causes stenosis of the second portion of the duodenum. In three cases, gastric outlet obstruction developed due to stenosis of the involved duodenum. Cystic change in the thickened duodenal wall is a characteristic feature and intraduodenal cysts are identified in 49% of patients with groove pancreatitis [5]. Lymphocyte infiltration, fibrosis or scarring in the groove area are also significant [1, 7]. In the present study, these histologic features were confirmed in 4 cases except in one case with distal common bile duct cancer.

The clinical manifestations of groove pancreatitis comprise upper abdominal pain, weight loss, postprandial vomiting and nausea due to duodenal stenosis, but jaundice is rare [7-9]. The chief complaint of all cases was epigastric or right upper quadrant abdominal pain in the present study. Clinical complications associated with groove pancreatitis are related to inflammatory changes affecting the duodenal wall. And major gastrointestinal hemorrhage, perforation, chronic debilitating abdominal pain, recurrent pancreatitis, duodenal stenosis, and, albeit a small risk, malignant transformation of ectopic pancreas have been reported [1, 8].

Upper endoscopy often shows an inflamed and polypoid duodenal mucosa with stenosis of the duodenal lumen [10]. EUS reveals smooth stenosis of the common bile duct; Santorini's duct is usually undetectable. Duct-penetrating signs are evident in the irregular hypoechoic mass [9]. In our experience, EUS was also effective in diagnosing groove pancreatitis. However, EUS makes insertion impossible due to duodenal stenosis and the accuracy of EUS is dependent on operator and experience. CT scan for groove pancreatitis reveals a hypodense, poorly enhanced mass between the pancreatic head and a thickened duodenal wall. Cystic lesions and a thickened duodenal wall are also useful indicators of groove pancreatitis on dynamic CT images [11]. Endoscopic retrograde cholangiopancreatography reveals tapering of the lower bile duct [9, 10]. When the duodenum of patients with groove pancreatitis is too narrow to perform gastrointestinal endoscopy and distinction between groove pancreatitis and pancreatic malignancy is difficult, magnetic resonance cholangiopancreatography is a useful diagnostic option [12].

Clinicians must consider peripancreatic cancer for a differential diagnosis of groove pancreatitis. The appearance of groove pancreatitis may resemble: 1) pancreatic diseases, such as acute pancreatitis; exophytic pancreatic ductal adenocarcinoma; or neoendocrine tumors; 2) bile ducts diseases such as cholangiocarcinoma and choledochal cysts; and 3) duodenal diseases. Other differential diseases include autoimmune pancreatitis and duodenal hamartoma [6]. In our experience, an older female without a history of alcoholism was diagnosed with groove pancreatitis by preoperative imaging studies including CT and EUS. Endoscopic biopsy demonstrated chronic inflammation. However, the final pathologic diagnosis was cholangiocarcinoma of distal common bile duct. Accordingly, careful follow-up of patients with a diagnosis of groove pancreatitis is necessary, because some conditions closely resemble peri-pancreatic carcinoma. And in cases where the diagnosis is in doubt, there are local complications, or when conservative treatment is ineffective, a pancreaticoduodenectomy with histological examination should be performed. In patients with groove pancreatitis, resection is often performed for the diagnosis of a peripancreatic malignancy [13].

Conservative treatments are to stop tobacco/alcohol consumption, recovery of pancreatic function, and analgesics. However, such treatments are only temporarily effective, as a rule [14]. Isayama et al. [15] reported the treatment of groove pancreatitis by endoscopic stenting of the minor papilla, but the long-term clinical course remains obscure.

Surgery is the treatment of choice when symptoms do not improve, or when the condition is too difficult to distinguish from pancreatic carcinoma. In a study by Rahman et al. [16], body weight increased and chronic abdominal pain was relieved in all patients who underwent pancreatoduodenectomy. Complete pain relief was reported in 76% of the patients after pancreatoduodenectomy [17]. There are three cases of 4 living patients who recovered from their pain after successful pancreaticoduodenectomy. The preservation of the pylorus during pancreaticoduodenectomy is not always feasible. We performed the Whipple procedure on one patient. We could not preserve the duodenal bulb and pylorus due to severe inflammation and mucosal erosion of his duodenal bulb. And we experienced two fatal complications including asphyxia and postoperative gastrointestinal bleeding. So, morbidity and mortality of pancreaticoduodenectomy should be considered.

In conclusion, patients with groove pancreatitis have clinical characteristics similar to those of chronic pancreatitis. The diagnostic imaging modalities of choice are computed tomography and endoscopic ultrasonography. And careful follow-up of patients is necessary if groove pancreatitis is suspected, because some conditions closely resemble peri-pancreatic carcinoma. Based on our surgical experience, pancreaticoduodenectomy seems to be a reasonable treatment option in patients with groove pancreatitis.