Groove pancreatitis: A case series and review of the literature

Introduction

Groove pancreatitis is a form of chronic segmental pancreatitis principally affecting the head of the pancreas. ¹ This rare form of pancreatitis is localised within the ‘groove’ between the head of the pancreas, the duodenum and the common bile duct with preservation of the main parenchyma and the main pancreatic ducts. ¹ The disease has a predilection for middle aged men with a previous history of chronic alcohol excess.^1–3 The exact prevalence of groove pancreatitis is difficult to assess but based on a number of surgical series, it appears to be within the range of 2.7–24.5% of patients with pancreatitis undergoing pancreaticoduodenectomy.^1–4 There have been reports of pancreatic cancer arising in the groove described as groove carcinoma. ⁵ Nevertheless differentiation of pancreatitis and cancer has proved difficult preoperatively. In this article, we present two cases of groove pancreatitis treated surgically in our unit over a 2-year period and a review of the literature to describe clinical, radiological and pathological characteristics of groove pancreatitis.

Case 1

A 47-year-old man, with a past history of excessive alcohol consumption was presented to the surgical department with epigastric pain associated with vomiting and weight loss. He had a history of recurrent admissions with abdominal pain secondary to recurrent alcohol-induced pancreatitis. Blood tests on this admission revealed a normal serum amylase and tumour markers. He underwent an oesophagogastroduodenoscopy (OGD) to further investigate the epigastric pain which revealed a duodenal diverticulum and a lesion with irregular nodularity in the second part of the duodenum and it was impossible to pass the gastroscope beyond the second part of the duodenum. Multiple duodenal biopsies were taken. Histological examination of the duodenal biopsies revealed prominent Brunner’s glands with no evidence of coeliac disease, giardiasis, dysplasia or malignancy. A CT scan of the pancreas showed several low density areas seen in the region of the pylorus, consistent with small pseudocysts (Figure 1). In order to further outline the pancreatic duct and the common bile duct, an MRCP was performed, which showed mild dilatation of the CBD which measured 1.1 cm with no intrahepatic biliary dilatation. Several pseudocysts medial to the gastric pylorus were noted. Considering the patient’s ongoing difficulty with eating, postprandial abdominal pain and continuing weight loss, it was decided that surgery was indicated. A laparotomy revealed an inflammatory mass in the head of the pancreas. A Whipple-type pancreaticoduodenectomy was performed. Histological examination of the specimen showed numerous small cysts varying in diameter from 10 to 20 mm within the wall of the duodenum and distal stomach. These cysts were partly formed by soft tissue from the head of the pancreas and did not appear to communicate with the duodenal lumen. The cysts were inseparable from the head of the pancreas. Microscopy of sections taken through the cyst revealed lumina sparsely lined by an attenuated poorly characterisable epithelium. Fibro-inflammatory tissue was seen to occupy the majority of the cyst wall. Characteristic of groove pancreatitis, the cysts were filled with eosinophilic amorphous material and a reactive spindle cell proliferation was observed (Figure 2). No evidence of malignancy was present. The patient had an uneventful post operative period and made a good recovery. Follow-up at 6 months was uneventful. OPEN IN VIEWER

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Figure 2.

Histopathology showing eosinophilic amorphous material, reactive plump spindle cell proliferation with admixed acute and chronic inflammatory cells, which merges gradually into dense fibrosis.

Case 2

A 54-year-old man was presented to the surgical unit with a 4-month history of epigastric pain and difficulty with eating. He was diagnosed with chronic pancreatitis 1 year previously and since then had six admissions with flare ups of his pancreatitis. There was no history suggestive of alcohol excess and the aetiology of his pancreatitis was unknown. A CT scan of the pancreas revealed a pancreatic head mass which was cystic in nature, measuring 7 × 5 cm ² with some calcifications (Figure 3). An OGD showed an area of stenosis of 2–3 cm length in the first part of the duodenum which extended to the margins of the second part. Multiple biopsies of the duodenum were taken. Histological examination of the fragments revealed acute-on-chronic inflammation with an increase of inflammatory cells within the lamina propria and areas of ingress of neutrophil polymorphs into the epithelium with no evidence of dysplasia or malignancy. The patient’s symptoms were ongoing despite conservative management and thus it was decided to proceed with surgery. A Whipple-type pancreaticoduodenectomy was performed. At laparotomy, a large mass in the head of the pancreas was noted with gross distortion of the first and second parts of the duodenum. Histological examination of the Whipple’s specimen revealed a grey/white mass occupying the entire pancreatic head. Numerous cystic spaces were noted between the duodenal wall and head of pancreas. Several firm white chalk-like calculi were also observed in the pancreatic head. Microscopy showed the cysts to have a partial epithelial lining. Some of the cysts were surrounded by a smooth muscle layer and areas of dense stromal tissue with abundant fibroblasts and myofibroblasts were also noted (Figure 4). There was no evidence of malignancy. A diagnosis of groove pancreatitis was made. The patient made a satisfactory recovery and was seen to be well at 6-month follow up. OPEN IN VIEWER

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Figure 4.

Histopathology showing the wall of the cyst composed of a reactive plump spindle cell proliferation with admixed acute and chronic inflammatory cells which merges gradually into dense fibrosis.

Discussion

Described in German literature by Becker in 1973 as ‘segmentare pankreatitis’, groove pancreatitis is characterised by fibrous scars of the anatomic space between the dorsocranial part of the head of the pancreas, the duodenum, and the common bile duct. ¹ Two forms of groove pancreatitis have been described in the literature; pure and segmental. ² The pure form of groove pancreatitis affects the groove only, and the segmental form involves the head of the pancreas, with scar tissue located in the groove. ²

The pathogenesis of groove pancreatitis is unclear with several possible aetiological factors appearing to contribute, of which pancreatic heterotopia in the duodenum or anatomic variation in the region of the minor papilla leading to outflow obstruction appears to be the most common cause. Associated alcohol intake appears to exacerbate it by increasing the pancreatic fluid viscosity by increasing the protein concentration. ⁴ The other possible aetiological factors include raised intraductal pressure within the accessory pancreatic duct resulting in pseudocyst formation and leakage of pancreatic juice into the groove. ²

The clinical picture is similar to that of chronic pancreatitis. The classical symptom is that of postprandial abdominal pain. Duodenal stenosis often leads to additional symptoms of early satiety, vomiting and weight loss. These symptoms can last for months to years and may become extremely debilitating. Jaundice is rarely seen and blood tests are commonly within normal limits. There may be a slight elevation of serum pancreatic enzymes and occasionally of liver function tests. ⁶ Tumour markers are rarely elevated.^1–3

Distinguishing between groove pancreatitis and pancreatic cancer poses a diagnostic challenge. OGD usually reveals a polypoid duodenal mucosa with inflammation and narrowing of the duodenal lumen. ⁷ Abdominal ultrasound often shows a hypoechoic mass, narrowing of the second part of the duodenum and signs of bile duct obstruction. ⁷ CT and MRI of the pancreas may be of diagnostic value in distinguishing the two entities. In cases of groove pancreatitis, CT depicts a poorly enhancing plate-like hypodense lesion between the pancreatic head and the duodenum, near the minor papilla whilst pancreatic malignancy often shows a mass in the head of the pancreas. ⁸ Cysts in the duodenal wall and in the groove and duodenal stenosis due to wall thickening can also be seen on CT in groove pancreatitis. ⁹ MRI has also been used to help diagnose groove pancreatitis and images including MRCP have been found to depict a sheet-like mass between the pancreatic head and the duodenum. ⁴ These radiological findings reflect the histological characteristics of the disease. Despite unique radiological features often pointing towards a diagnosis of groove pancreatitis, these are not always present and a surgical dilemma frequently ensues. A recent case report by Malde et al. describes a case where an initial diagnosis of groove pancreatitis was made based on symptoms and radiological features. As the clinical picture changed a Whipples was performed and a definitive diagnosis of pancreatic adenocarcinoma was made, making surgical intervention the best investigative modality to differentiate the two pathologies and exclude malignancy. ⁹

Conservative measures including analgesics, pancreatic rest, and abstinence from alcohol are usually successful at treating initial symptoms, but may not be long lasting. Endoscopic drainage of a stenotic or occluded minor duct has been reported with good initial results. The presence of intractable pain and/or pancreatic insufficiency (weight loss, steatorrhoea or diabetes), can be attributed to the severe inflammatory and fibrotic changes observed in the head of pancreas often associated with duodenal obstruction secondary to scarring or cystic dystrophy. Some others have advocated an initial gastroenterostomy to relieve the obstruction. However, a pancreaticoduodenectomy (PD) may be required at a late phase of the disease, resulting in symptomatic relief and can lead to adequate weight gain. In addition a PD is often required to definitively rule out a pancreatic neoplasm. ⁵ In the present series both patients exhibited characteristic clinical, radiological and pathological features consistent with a diagnosis of groove pancreatitis. This case series highlights the need for awareness and a high index of suspicion of this pathological entity in patients with focal pancreatic lesions with stenosis of the papilla in association with alcohol excess. Surgery remains the mainstay of treatment in the presence of on-going obstructive symptoms, and also to exclude occasional adenocarcinoma of the pancreas that mimics an inflammatory mass in this location.

Conclusions

Groove pancreatitis is a specific disease entity, with unique symptomatology and characteristic radiological and histological findings. Recent case series have shown that groove pancreatitis can often be diagnosed based upon symptoms and radiological findings alone. Since these characteristics may also mimic those of classic pancreatitis and pancreatic malignancy, clinicians should be familiar with groove pancreatitis to ensure the correct diagnosis and surgical management of this often debilitating condition.