Inflammatory pseudotumors (ITP) are rare nonencapsulated solid tumorlike lesions of unclear etiology that can be found in multiple organ systems. The lesions are comprised of aggregations of inflammatory cells surrounded by a proliferative fibrous stroma and are generally considered benign in nature. However, the constellation of presenting symptoms and the radiographic appearance of ITP of the pancreas are often consistent with a pancreatic malignancy, and operative resection of these lesions is necessary to rule out a malignant process. We present the case of an 82-year-old woman who to our knowledge is the first reported case of pancreatic IPT treated laparoscopically.

Case report

An 82-year-old woman with a medical history of non–insulin-dependent diabetes and hypertension presented with a 2-month history of intermittent nausea and vomiting after meals and postprandial abdominal pain. The patient had sustained a 25-lb weight loss and systemic complaints of generalized fatigue over the preceding 6 months. The patient denied alcohol or tobacco use and stated no risk factors for pancreatitis.

Physical exam revealed a thin but well-appearing elderly woman with a soft abdomen and no palpable abdominal masses and adenopathy. Laboratory examination—including complete blood count, amylase, lipase, liver function tests, and triglycerides—revealed no significant abnormalities. Abdominal ultrasound showed no evidence of biliary disease. Esophagogastroduodenoscopy, colonoscopy, and gastric emptying studies demonstrated only diverticulosis and evidence of gastroparesis. A CT scan of the abdomen and pelvis revealed an irregularity in the tail of the pancreas consistent with a pancreatic neoplasm, but there was no evidence of pancreatitis, pancreatic duct dilation, adenopathy, or metastatic disease. An MRI confirmed the presence of a 2.5 × 1.9 cm mass located in the pancreatic tail (Fig. 1). The lesion appeared to be confined to pancreatic parenchyma and was not associated with evidence of metastasis.

Figure 1
figure 1

MRI scan of the abdomen with gadolineum revealing a 1.5 × 2.5 cm mass (arrowheads) in the tail of the pancreas. The mass showed delayed uptake of gadolineum relative to surrounding pancreas and appeared to be confined to the pancreas, with extension to adjacent structures.

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Because of the concern regarding malignancy, the patient was brought to the operating room for laparoscopic distal pancreatectomy and splenectomy, which proceeded without complications. At exploration, a solid, nonencapsulated lesion confined to the parenchyma of the tail of the pancreas was discovered (Fig. 2). No evidence of metastatic disease was present. Complete mobilization and resection of the spleen and pancreatic tail en bloc was performed laparoscopically. A Harmonic Scalpel was used for dissection and an endo-GIA stapler with 2.5-mm staples for dividing the pancreas. The specimen was removed from the abdomen via a small upper midline incision and a wound protection device.

Figure 2
figure 2

Intraoperative view of atrophic pancreas with tumor in situ (arrowheads) in the distal pancreatic tail. The short gastric arteries (asterisks) have been divided from the spleen (sp) with the Harmonic Scalpel.

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On intraoperative frozen sections of the tumor, we were unable to differentiate between low-grade carcinoma and chronic pancreatitis. However, permanent histology revealed that the lesion was a benign inflammatory pseudotumor with chronic fibrosing pancreatitis (Fig. 3).

Figure 3
figure 3

A Low-power view of the fibrotic pancreas showing dense fibrosis and lymphoid follicles scattered throughout the lesion. B Paucicellular fibrotic process composed of interlacing bands of myofibroblasts centered on blood vessel walls with a dense inflammatory infiltrate of lymphocytes and plasma cells (×100)

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The patient underwent an uneventful recovery and was discharged home on the 4th postoperative day. At 12-month follow-up, the patient had achieved stabilization of her weight and complete resolution of her abdominal symptoms. She remains free of evidence of recurrent or multifocal disease.

Discussion

Inflammatory pseudotumor (IPT) is a rare pathologic entity characterized by inflammatory and fibrous components. Histologic examination of this lesion reveals centrally localized mononuclear cells including lymphocytes, eosinophils, macrophages, plasma cells, and mast cells surrounded by proliferation of spindle cell–shaped mesenchymal cells and fibroblasts [7, 23]. Because of its variable histology, this entity has been referred to by a variety of terms, including inflammatory myofibrohystiocytic proliferation, inflammatory myofibroblastic tumor, and plasma cell granuloma. IPT is generally considered to be a benign lesion without malignant histologic features. However, recent reports of local recurrence and progressive multifocal disease have led some investigators to emphasize their potential for aggressive behavior and propose the possibility of malignant degeneration of pseudotumor lesions [5, 8, 12, 29].

Although IPT is most commonly seen in the lung, multiple extrapulmonary sites have been described, including liver, spleen, intestinal mesentery, lymphatics, and pancreas [6, 7].

Pancreatic IPT is rare, with only 27 reported cases in the English literature [1, 2, 3, 4, 9, 10, 11, 13, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 30]. Patients with pancreatic IPT generally fall into two categories—those associated with retroperitoneal fibrosis and those isolated to the pancreas.

Patients with retroperitoneal fibrosis are often older individuals who present with abdominal pain, jaundice, and weight loss. Although operative exploration and resection of the pancreatic mass remains the mainstay of therapy for these patients, there have been several reports of regression of the pancreatic IPT and resolution of symptoms after corticosteroid therapy [3, 4, 11].

IPT isolated to the pancreas can have a variety of presentations. Many of these presentations can be attributable to local effects of the mass; they include abdominal or back pain, anorexia, nausea, emesis, weight loss, jaundice, anemia, and fatigue [13, 23]. The etiology of pancreatic IPT is unclear. The pathogenesis of this lesion may involve autoimmune processes; various authors have shown associations between IPT of the pancreas and other autoimmune-mediated diseases, such as Crohn’s colitis, Sjogren’s syndrome, retroperitoneal fibrosis, and idiopathic thrombocytopenic purpura [13, 22, 25]. An infectious etiology may also play a role in the development of this lesion. It has been hypothesized that an infectious agent may incite a localized immune response, leading to the recruitment of inflammatory cells and development of the fibrous changes seen in this lesion. Epstein-Barr virus (EBV) may be a likely candidate for this infectious agent because it has been identified in IPT of the liver and spleen [2, 15]. However, pancreatic IPT lesions that have been tested have not yet shown EBV [19].

The presentation and radiographic appearance of pancreatic IPT usually mandates operative exploration and pancreatic resection to rule out malignancy. Rarely is the diagnosis made preoperatively, although it can be suspected in the patient who has a pancreatic mass in the setting of an associated condition such as sclerosing cholangitis or retroperitoneal fibrosis. Even in such patients, care must be taken when contemplating nonoperative therapy in a patient with a potential pancreatic malignancy.

Resection can be attained either by pancreaticoduodenectomy, distal pancreatectomy, or total pancreatectomy, and resection often results in the resolution of the presenting symptoms. In all previous reports of resection of pancreatic IPT, laparotomy and open resection were used. Although laparoscopic splenectomy has been reported for splenic IPT, this is the first reported case of pancreatic IPT resected laparoscopically [27].

The prognosis of patients with pancreatic IPT is quite favorable. Resection by partial pancreatectomy or pancreaticodoudenectomy usually decreases or eliminates presenting symptoms of abdominal pain, nausea, and biliary obstruction. Although several authors have reported the development of subsequent multifocal ITP or local recurrence after resection, most patients undergo curative resection and remain free of disease at follow-up [5, 8, 12, 29].

Conclusion

Inflammatory pseudotumor of the pancreas is a rare entity that can present clinically and radiographically as a malignant lesion of the pancreas. For this reason, these lesions are generally treated by resection in appropriate surgical candidates. Laparoscopic distal pancreatectomy is an alternative to open resection in patients with lesions in the tail of the pancreas. Microscopic examination of IPT reveals a benign lesion, and thus complete resection results in definitive treatment.