Pancreatic malignant fibrous histiocytoma, inflammatory myofibroblastic tumor, and inflammatory pseudotumor related to autoimmune pancreatitis: characterization and differential diagnosis

Primary Pancreatic Undifferentiated Pleomorphic Sarcoma

Primary pancreatic sarcomas are rare malignancies with an incidence of 0.1%. This case report is of a 48-year-old man who presented with this condition. The patient's treatment plan consisted of distal pancreatectomy and splenectomy with intraoperative immunohistochemistry and adjuvant chemotherapy. To correctly identify and treat undifferentiated pleomorphic sarcoma, a stepwise strategy involving cross-sectional imaging and extensive histopathology analysis is necessary.

Undifferentiated pleomorphic sarcoma of the pancreas: a rare case report and literature review

Background

Primary undifferentiated pleomorphic sarcoma (UPS) of the pancreas is an exceedingly rare malignant tumor, with only 15 cases have been reported in the medical literature. At present, clinicians have poor recognition of the tumor, the epidemiology, diagnosis, and treatment of this disease have yet not been established.

Case presentation

In this report, we depict the clinical and imaging characteristics of a 37-year-old man presenting with a primarily cystic UPS. The patient complained of epigastric pain and distention over 20 days. Abdominal CT and pancreatic magnetic resonance imaging revealed cystic and cystic solid masses in the pancreatic body and tail. An abdominal ultrasound echogram revealed the mass in the body of the pancreas to be cystic with separation echo inside, and the wall was thick, not smooth. Besides, a hypoechoic mass was seen in the tail area of the pancreas with an inhomogeneous echoic pattern, containing small patches of no echo zone in the central. Microscopically, spindle fibroblast-like cells are arranged in a characteristic storiform pattern with pleomorphic and multinucleated cells. Immunohistochemically, tumor cells were positive for CD68 and vimentin. Seven months postoperatively, he was diagnosed with pulmonary lymph node metastasis and died 5 months later. Combined with this case report, we also reviewed the literature regarding UPS of the pancreas.

Conclusions

As we know, this is the first report on ultrasonography findings of pancreatic UPS. Despite there are no distinctive manifestation of UPS, a solid cystic lesion on ultrasonography or a hypodense area in the lesion on T2-weighted imaging, should be considered for differential diagnosis with pancreatic UPS. We believe this article may add some ideas into the diagnosis and therapy of patients with this tumor.

A Pancreatic Inflammatory Myofibroblastic Tumor with Spontaneous Remission: A Case Report with a Literature Review

The inflammatory myofibroblastic tumor (IMT) is a rare tumor that can develop in any systemic organ. Its features are generally benign, but it often resembles malignancies and is treated surgically. Our patient was an 82-year-old female complaining of abdominal discomfort. Computed tomography demonstrated a 5 cm, ill-enhanced mass at the pancreas head. Upper gastrointestinal endoscopy revealed a duodenal submucosal tumor with apical erosion. Endoscopic ultrasonography (EUS) demonstrated a heterogeneous, low-echoic pancreas mass without clear margins. Fine-needle aspiration biopsy (FNAB) demonstrated spindle myofibroblastic tissues with lymphoplasmacyte and eosinophil infiltration, confirming an IMT diagnosis. Surprisingly, the tumor spontaneously regressed in one month without medication. Histological diagnosis using EUS-FNAB is essential for the rare pancreatic solid tumor like IMT.

Spontaneous pancreatic undifferentiated pleomorphic sarcoma in a laboratory rat: A case report

We present a case of spontaneous undifferentiated/unclassified sarcoma, of a pleomorphic subtype formerly known as malignant fibrous histiocytoma (UPS/MFH), arising from the pancreas of a laboratory rat. The mass was excised after laparotomy from a 6-month-old female laboratory Wistar rat. It presented a giant multilobulated mass of irregular shape, which had arisen from the pancreas and occupied almost the entire peritoneal cavity. Histologically the tumor was characterized by a highly variable morphological pattern, with frequent transitions from storiform to pleomorphic areas. An extensive immunohistochemical examination revealed no specific lines of differentiation. Immunohistochemical positivity was observed only to MIB-1 (high Ki-67 proliferation index), vimentin and CD68 antibodies. The diagnosis was compatible with UPS/MFH. To the best of our knowledge, the present case is the first report of a spontaneous primary UPS/MFH arising from the pancreas of a laboratory rat.

Inflammatory Pseudotumor of the Pancreas Mimicking a Pancreatic Neoplasm

A 78-year-old woman was admitted to our hospital with a pancreatic tumor, incidentally discovered in an abdominal ultrasound exam. She was asymptomatic and without any previous personal pathological condition. The computed tomography (CT) and the magnetic resonance imaging (MRI) scan showed a mass lesion of 4 cm in diameter, located in the pancreatic body, conditioning the invasion of the splenic vein. The patient was admitted to surgery. During the laparotomy, we found a tumoral lesion highly suspicious of pancreatic neoplasia located in the transition of the head/body of the pancreas, with an invasion of the portal vein and several peri-regional lymph nodes. We performed biopsies of the pancreatic mass and lymphadenectomy of the peri-regional pancreatic lymph nodes. Histological analysis found an inflammatory pseudotumor of the head/body of the pancreas, without signals of malign epithelial neoplasm and also without criteria for immunoglobulin G4-related disease. During the follow-up, a PET/CT and MRI confirmed that the pancreatic lesion had disappeared without any treatment. Inflammatory pseudotumor of the pancreas is a rare entity not fully understood. Despite this, the administration of corticosteroids and immunosuppressive therapy could be taken into consideration as the disease carries a risk.

Benign Tumors and Tumorlike Lesions of the Pancreas

The pancreas is a complex organ that may give rise to large number of neoplasms and non-neoplastic lesions. This article focuses on benign neoplasms, such as serous neoplasms, and tumorlike (pseudotumoral) lesions that may be mistaken for neoplasm not only by clinicians and radiologists, but also by pathologists. The family of pancreatic pseudotumors, by a loosely defined conception of that term, includes a variety of lesions including heterotopia, hamartoma, and lipomatous pseudohypertrophy. Autoimmune pancreatitis and paraduodenal ("groove") pancreatitis may also lead to pseudotumor formation. Knowledge of these entities will help in making an accurate diagnosis.

Benign inflammatory pseudotumour mimicking extrahepatic bile duct cholangiocarcinoma in an adult man presenting with painless obstructive jaundice

Inflammatory pseudotumours (IPTs) of the biliary tract are extremely rare and heterogeneous by aetiology and clinical presentation. They might cause biliary obstruction and mimic cholangiocarcinomas and their final diagnosis is usually achieved only after surgical excision. The most characteristic feature of IPT is the presence of chronic inflammatory cell infiltrates with variable degree of proliferating fibrous tissue. IPTs have the potential for recurrence even after resection and if untreated they can grow causing a variety of symptoms due to compression of the surrounding structures and organs. Despite the significant improvement of modern imaging techniques, preoperative distinction between IPTs of the biliary system and malignancies is extremely difficult. Histological diagnosis poses a clinical challenge because sampling is often suboptimal. Although rare, IPTs should be in the differential diagnosis of patients who present with painless jaundice and no other clinical symptoms or signs characteristics of cholangiocarcinomas.

Prevalence of autoimmune pancreatitis and other benign disorders in pancreatoduodenectomy for presumed malignancy of the pancreatic head

BACKGROUND

Occasionally patients undergoing resection for presumed malignancy of the pancreatic head are diagnosed postoperatively with benign disease. Autoimmune pancreatitis (AIP) is a rare disease that mimics pancreatic cancer. We aimed to determine the prevalence of benign disease and AIP in patients who underwent pancreatoduodenectomy (PD) over a 9-year period, and to explore if and how surgery could have been avoided.

METHODS

All patients undergoing PD between 2000 and 2009 in a tertiary referral centre were analyzed retrospectively. In cancer-negative cases, postoperative diagnosis was reassessed. Preoperative index of suspicion of malignancy was scored as non-specific, suggestive, or high. In AIP patients, diagnostic criteria systems were checked.

RESULTS

A total of 274 PDs were performed for presumed malignancy. The prevalence of benign disease was 8.4 %, overall prevalence of AIP was 2.6 %. Based on preoperative index of suspicion of malignancy, surgery could have been avoided in 3 non-AIP patients. All AIP patients had sufficient index to justify surgery. If diagnostic criteria would have been checked; however, surgery could have been avoided in one to five AIP patients.

CONCLUSIONS

The prevalence of benign disease in patients who underwent PD for presumed malignancy was 8.4 %, nearly one-third attributable to AIP. Although misdiagnosis of AIP as carcinoma is a problem of limited quantitative importance, every effort to establish the correct diagnosis should be undertaken considering the major therapeutic consequences. IgG4 measurement and systematic use of diagnostic criteria systems are recommended for every candidate patient for PD when there is no histological proof of malignancy.

Pancreatitis, Other Inflammatory Lesions, and Pancreatic Pseudotumors

The pancreas is versatile in the diversity of disorders that it can exhibit. In this article, characteristics of disorders such as chronic, autoimmune, eosinophilic, hereditary, and infectious pancreatitis are described. With regard to autoimmune pancreatitis, the role of clinical evaluation, histologic examination, and IgG4 immunohistochemistry is discussed. The role of pancreatitis in the pathogenesis of diabetes is also mentioned. Some implications of pancreatitis are highlighted, including the neoplastic predisposition caused by inflammatory lesions of the pancreas. The goal of this article is to convey an appreciation of these disorders because their recognition can benefit patients tremendously, as inflammatory lesions of the pancreas can be mass-forming, giving rise to pseudotumors, and leading to surgical resection that may otherwise be unnecessary.

Complete Long-Term Remission of an Inflammatory Pseudotumor under Corticosteroid Therapy

Inflammatory pseudotumors (IPT) form a group of etiologically, histologically, and biologically heterogeneous tumefactive lesions that are histologically characterized by prominent inflammatory infiltrates. IPT has been described in various organs including the lungs, bladder, liver, spleen, heart, and others. It may mimic a malignant tumor clinically and radiologically. We report a case of a 26-year-old woman with an ALK1-negative IPT (7 cm in maximal diameter) mainly located in the 12th right back muscles, surrounding a fractured rib. Histologically, the tumor consisted of an inflammatory infiltrate composed predominantly of diffusely distributed lymphoplasmacytic cells and stromal fibroblasts associated with focal obliterative phlebitis. Conservative steroid treatment resulted in complete remission and the patient remained disease-free for more than 1 year later. To our knowledge this is the first report of IPT involving the skeletal back muscle and complete resolution under corticosteroid treatment.

First case of primary phyllodes tumor of the pancreas: case report and findings of immunohistochemical and ultrastructural studies

A 37-year-old Japanese man with a solid and cystic pancreatic mass was referred to our hospital. Computed tomography revealed a well-demarcated solid and cystic mass measuring approximately 3.0 cm in diameter in the pancreatic body. The patient underwent middle segment pancreatectomy, and the retrieved tumor specimen was found to be a well-demarcated solid and cystic lesion measuring 3.0 x 3.0 cm. On histological examination, the cyst walls were found to be lined with a monolayer of non-atypical tall columnar epithelial cells. The solid areas surrounded the cystic ones and showed storiform proliferation of spindle cells that contained round, oval, or elongated nuclei and were present among abundant collagen fibers. The solid areas sent phylloid projections into the cystic spaces and the main pancreatic duct. The spindle cells were found to be diffusely positive for alpha-smooth muscle actin, desmin, and h-caldesmon on immunohistochemical analysis. Electron microscopy revealed that these cells possessed well-developed myofilaments with dense bodies, pinocytic vesicles, and basal lumina. Neither metastasis nor local invasion was detected. After the operation (4 years), tumor recurrence has not occurred. The main differential diagnoses of spindle cell tumors are leiomyomas, leiomyosarcomas, inflammatory myofibroblastic tumors, solitary fibrous tumors, extra-gastrointestinal stromal tumors, and schwannomas. However, the histological findings in the present case differed from those of these tumors. The present lesion is the first reported case of a primary pancreatic phyllodes tumor.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Spontaneous development of a pancreatic exocrine disease in CD28-deficient NOD mice

Autoimmune pancreatitis (AIP) is a heterogeneous autoimmune disease in humans characterized by a progressive lymphocytic and plasmacytic infiltrate in the exocrine pancreas. In this study, we report that regulatory T cell-deficient NOD.CD28KO mice spontaneously develop AIP that closely resembles the human disease. NOD mouse AIP was associated with severe periductal and parenchymal inflammation of the exocrine pancreas by CD4(+) T cells, CD8(+) T cells, and B cells. Spleen CD4(+) T cells were found to be both necessary and sufficient for the development of AIP. Autoantibodies and autoreactive T cells from affected mice recognized a approximately 50-kDa protein identified as pancreatic amylase. Importantly, administration of tolerogenic amylase-coupled fixed spleen cells significantly ameliorated disease severity, suggesting that this protein functions as a key autoantigen. The establishment and characterization of this spontaneous pancreatic amylase-specific AIP in regulatory T cell-deficient NOD.CD28KO mice provides an excellent model for the study of disease pathogenesis and development of new therapies for human autoimmune pancreatitis.

Autoimmune pancreatitis: expression and cellular source of profibrotic cytokines and their receptors

Chronic pancreatitis is a fibrogenic disease. In autoimmune pancreatitis (AIP), a lymphoplasmacytic infiltration is followed by fibrosis. In vitro it has been shown that pancreatic stellate cells are transformed into proliferating myofibroblasts mainly by transforming growth factor beta (TGF-beta) and platelet-derived growth factor (PDGF). We studied the expression of these profibrotic cytokines, their receptors, and their cellular sources in AIP. Pancreatic tissues from 21 patients with AIP of different grades of severity were selected from a series of 52 AIP cases. Myofibroblasts (ie, activated pancreatic stellate cells), macrophages, lymphocytes, plasma cells, and the cytokines latency-associated peptide, a TGF-beta1 propeptide, TGF-beta receptor II (TGF-beta-RII), PDGF-B, and the alpha and beta isoforms of the PDGF receptor (PDGF-R alpha and PDGF-R beta) were identified immunohistochemically. Their expression and cellular distribution were related to the severity of AIP. In grade 1 and 2 AIP, macrophages and myofibroblasts expressing profibrotic cytokines and their receptors were found in periductal areas showing lymphoplasmacytic inflammation. In grade 3 AIP, there were numerous macrophages, myofibroblasts, and epithelial cells which were positive for latency-associated peptide, PDGF-B, TGF-beta-RII, PDGF-R alpha, and PDGF-R beta not only in periductal, but also in interlobular and intralobular areas. In grade 4 AIP, which is characterized by advanced fibrosis, cellularity and expression of cytokines and their receptors were greatly reduced. Our data indicate that in AIP the occurrence of myofibroblasts is intimately related to the presence of macrophages and lymphoplasmacytic cells. These cells and adjacent epithelial cells express profibrotic cytokines and their receptors, which are probably responsible for the initiation and maintenance of the fibrogenic process.

A case of primary malignant fibrous histiocytoma of the pancreas: CT and MRI findings

Primary malignant fibrous histiocytoma (MFH) of the pancreas is rare and a distinct clinical entity. We report a case of recurrence of pancreatic MFH with computed tomography (CT) and magnetic resonance imaging (MRI) findings. A 67-year-old man presented with a history of decreased body weight over the past 6 mo. Abdominal CT revealed a large, multilocular cystic mass in the head of the pancreas with obvious atrophy in the body and tail of the pancreas. After 6 mo postoperatively, MRI demonstrated a recurrent large mass in the primary area of the head of the pancreas. The lesion was heterogeneous, hypointense to the liver on T1-weighted imaging, and heterogeneously hyperintense to the liver with a hypointense area in the central part of the tumor on fat-saturated T2-weighted imaging. Contrast-enhanced T1-weighted imaging demonstrated a large multilocular cystic mass with a cystic wall, fibrous septa and enhancement of solid components. To the best of our knowledge, this is the first report on recurrence of primary MFH of the pancreas, and the first with MRI findings.

Bilateral infiltrating renal inflammatory pseudotumor responsive to corticosteroid therapy

Inflammatory pseudotumor (IPT) is a quasi-neoplastic lesion that most commonly involves the lung, but has been shown to occur in nearly every tissue type. Renal involvement is very uncommon. We report the second case of IPT ever published presenting as bilateral infiltrating renal masses. Although most renal IPTs were treated with nephrectomy, our patient was managed successfully with conservative steroid treatment, thereby avoiding the alternative of dialysis or kidney transplantation.

Solid pancreatic hamartoma

A case of solid pancreatic hamartoma in a 58-year-old Japanese woman is presented. She had no symptoms, and a pancreatic mass was incidentally found on screening ultrasonography 4 months before admission. The patient was not alcoholic and had no history of pancreatitis. Physical examination and laboratory data were unremarkable. Preoperative imaging demonstrated a nodule in the body of the pancreas, measuring 2.0 cm in maximum diameter, which showed marked delayed enhancement during dynamic CT. The patient underwent a distal pancreatectomy under the preoperative diagnosis of pancreatic endocrine tumor and had an uneventful postoperative course. A well-demarcated solid nodule, 1.9 cm in diameter, was evident in the body of the pancreas. Microscopically, the lesion was composed of non-neoplastic, disarranged acinar cells and ducts embedded in a sclerotic stroma with elongated spindle cells, lacking discrete islets. The stromal spindle cells were immunoreactive for CD34 and CD117. The histological diagnosis was solid hamartoma of the pancreas. There was no recurrence 5 months after surgery. Herein is reported a case of solid hamartoma of the pancreas and review of the literature. A search through the literature found only two cases of solid hamartoma of the pancreas, among the 14 cases previously reported as pancreatic hamartoma.

Autoimmune Pancreatitis: Frequency, IgG4 Expression, and Clonality of T and B Cells

Autoimmune pancreatitis (AIP) is a newly recognized disease. The presence of IgG4 positive plasma cells is thought to be of diagnostic help. In a surgical series of chronic pancreatitis cases, we determined the relative frequency of AIP before and after 1990, analyzed the diagnostic significance of IgG4 expression and examined the presence of oligoclonal T or B-cell populations. The histopathology of 202 surgical specimens of chronic pancreatitis removed between 1975 and 2004 was reviewed and 2 groups were distinguished, 1 of AIP cases and the other of nonautoimmune chronic pancreatitis (non-AIP CP). The intensity of infiltration of pancreatic tissue by IgG4 positive plasma cells and other immune cells was studied immunohistochemically. Finally, T and B-cell clonality was tested by polymerase chain reaction-based analysis. Except for 1 case in 1978, all cases of AIP were observed after 1990. IgG4 positive plasma cells were detected in 72.5% of AIP cases and in 63.1% of non-AIP CP cases. More than 20 cells per high power field were only seen in AIP (sensitivity 43%, specificity 100%). This finding was associated with higher age and grade. Polyclonal T and B-cell populations were found in both AIP and non-AIP CP except for 1 AIP case showing an oligoclonal IgGH-FR3 gene rearrangement. AIP seems to have increased considerably in frequency in the last 2 decades. High density infiltrates of IgG4 positive plasma cells are diagnostic for AIP, but are seen in less than half of the cases. T or B-cell oligoclonality could not be established as a feature of AIP.

Chronic pancreatitis, pseudotumors and other tumor-like lesions

Chronic pancreatitis is a fibroinflammatory disease of the pancreas. Etiologically, most cases are related to alcohol abuse and smoking. Recently, gene mutations have been identified as the cause of hereditary pancreatitis. Other chronic pancreatitis types that were defined in recent years are autoimmune pancreatitis (lymphoplasmacytic sclerosing pancreatitis) and paraduodenal pancreatitis ('groove pancreatitis', 'cystic dystrophy of heterotopic pancreas'). This review describes and discusses the main histological findings, the pathogenesis and the clinical features of the various types of chronic pancreatitis. In addition, pseudotumors and other tumor-like lesions are briefly mentioned.

Diagnostic features and differential diagnosis of autoimmune pancreatitis

A clinically and pathologically distinct form of chronic pancreatitis is now widely recognized and has been designated variably as lymphoplasmacytic sclerosing pancreatitis, duct-destructive (duct-centric) pancreatitis or autoimmune pancreatitis. This entity is currently defined by a constellation of clinical and pathologic findings, including the lack of both conventional risk factors for pancreatitis, such as alcohol use and gallstones, and their hallmark pattern of injury, including calcifications and pseudocysts. Histologically, it is characterized by lymphoplasmacytic inflammation with abundant IgG4-positive plasma cells that exhibit an affinity for ducts as well as venules ("peri-venulitis," with or without frank vasculitis). Inflammation is often associated with sclerosis and expansion of periductal tissue. In some cases, fibroblastic activity is prominent and resembles "inflammatory pseudotumor" or is even misdiagnosed as "inflammatory myofibroblastic tumor." In what appears to be a distinct subset of this entity, intraepithelial granulocytic infiltrates may be seen. Well-developed examples are readily recognized; however, lesser ones may be difficult to distinguish from other forms of pancreatitis based on morphology alone. This type of pancreatitis is considered an autoimmune process. In about 15% to 20% of patients, the clinical stigmata of autoimmune conditions are present at the time of diagnosis, and in many others, discovered subsequently. The usual "lymphoplasmacytic sclerotic" type tends to be associated with Sjogren, whereas the "granulocytic" subset, with inflammatory bowel disease. Most patients present with a pancreatic head mass, often with an accompanying stricture of the distal common bile duct, which thus radiologically resembles "pancreas cancer." In fact, this entity accounts for more than a third of the cases of pseudotumoral pancreatitis (mass-forming inflammatory lesions that resemble carcinoma). Elevated serum IgG4 levels are characteristic and may be very helpful in the differential diagnosis from tumors and tumor-like lesions of the pancreas which seldom result in levels above 135 mg/dL. The mean age of the patients with this condition is in the mid-50s; the subset with granulocytic intraepithelial lesions seem to be younger (mid 40s). Despite the autoimmune association, males are afflicted as commonly as (if not more than) females. Following resection, emergence of new fibro-inflammatory lesions in the remaining pancreaticobiliary tree has been noted in some cases; however, the process typically responds to steroids. It is important to recognize the distinctive clinicopathologic features of this entity, so that it can be diagnosed accurately and managed appropriately.