Syn: Inflammatory pseudotumor ; Plasma cell granuloma

Pancreatic inflammatory pseudotumor is a rare lesion of the pancreas but it must be distinguished from pancreatic cancer.

The tumour is more common in lung.

Visit: Inflammatory Pseudotumour of the Lung ; Myofibroblastic tumours of the soft tissue .

The lesion is probably not EBV-related.

Clinically the lesion generally presents with cholestasis and a mass lesion which may constrict bile duct  suspicious of malignancy,

Histologically, there is a hypocellular to moderately hypercellular, bland spindle-cell proliferation admixed with a prominent infiltrate of lymphocytes, histiocytes and plasma cells . In rare cases, eosinophils are prominent.

The spindle cells are vimentin and smooth muscle actin positive. The lesion is negative for  S100, CK, CD35, LMP, EBER.

It can be extremely difficult to differentiate inflammatory myofibroblastic tumour from pancreatic malignancies.

Most cases require surgical exploration and complete resection to obtain an accurate diagnosis.

Pancreatic masses could be malignant or benign. Among these latter inflammatory pseudotumor is an uncommon mass rarely located in the pancreas and it must be considered in differential diagnosis with pancreatic cancer. A case report and literature review of inflammatory pseudotumor were recognized to well known this rare pathology regarding its clinical, diagnostic, therapeutic and histopathological feature. Twenty-one cases of inflammatory pseudotumor in the adult were reviewed from the literature; 10 (47.6%) were female, 11 (52.3%) male; mean age 53.3 years (range 23-73). They were solid single mass in 18 cases, with median size of 5.1 cm (range 1.5-13), cystic mass in one case; 18 were located in the head, 1 in the body. In 2 cases it appeared as a volumetric increase of the pancreas. Diagnosis was possible only histologically and surgical treatment was mandatory in 20 cases; only in one patient a corticosteroid treatment was performed. Pancreatic inflammatory pseudotumor is a rare lesion of the pancreas but it must be distinguished from pancreatic cancer. Pancreatic resectioning is mainly due to the preoperative diagnostic difficulties that must be resolved surely only with histopathological examination of the specimen.

Inflammatory myofibroblastic tumor presenting as a pancreatic mass: a case report and review of the literature.JOP. 2004 Sep 10;5(5):360-7.

CONTEXT: Inflammatory myofibroblastic tumor is a distinctive lesion of unknown etiology. It has generally been considered a rare benign pseudosarcomatous lesion of admixed inflammatory infiltrates with myofibroblastic spindle cells. Although original case descriptions focused on the pulmonary system, it is now recognized that virtually any anatomic location can be involved. However, an inflammatory myofibroblastic tumor located in the pancreas is rare. CASE REPORT: We report a case of an asymptomatic 70-year-old Caucasian man with a 3.8 cm inflammatory myofibroblastic tumor located in the tail of the pancreas which was discovered incidentally on a computed tomography scan of the abdomen. Endoscopic ultrasonography with fine needle aspiration was negative for malignancy. However, because of worrisome radiographic features, a distal pancreatectomy with splenectomy was performed. The pathology revealed an inflammatory myofibroblastic tumor with focal extension into the peripancreatic soft tissues, but with negative surgical margins. The patient has been followed for 10 months without evidence of recurrence. CONCLUSIONS: To date, there have been only 25 cases of inflammatory myofibroblastic tumor located in the pancreas reported in the English language scientific literature. Even with multimodal pre-surgical investigation, it can be extremely difficult to differentiate inflammatory myofibroblastic tumor from pancreatic malignancies. Most cases require surgical exploration and complete resection to obtain an accurate diagnosis. A review of published case reports is also presented.

Laparoscopic distal pancreatectomy for inflammatory pseudotumor of the pancreas.Surg Endosc. 2004 Jun;18(6):1001. 

An 82-year-old woman presented with abdominal pain, nausea, emesis, and weight loss of ~25 lb over 6 months. A CT scan and MRI of the abdomen revealed a mass in the tail of the pancreas that was suspicious for malignancy. The patient underwent successful laparoscopic distal pancreatectomy and was discharged home on the 4th postoperative day after an uneventful course. Pathology revealed an inflammatory pseudotumor of the pancreas (IPT). Pancreatic IPT is a rare entity, and this case represents the first report of laparoscopic resection of this lesion. The presentation, diagnosis, histologic features, and therapy of IPT of the pancreas are reviewed.

Oligoclonal T-cell populations in an inflammatory pseudotumor of the pancreas possibly related to autoimmune pancreatitis: an immunohistochemical and molecular analysis.Virchows Arch. 2004 Feb;444(2):119-26.

Inflammatory pseudotumors (IPT), also known as inflammatory myofibroblastic tumors (IMT), are benign inflammatory processes that may have an infectious etiology and are very rare in the pancreatico-biliary region. Recent studies suggest a biological distinction between IPT and IMT, the latter being a true neoplastic process. We describe a case of pancreatic IPT, originally diagnosed as malignancy, which presumably recurred 4 months after the operation. Histologically, the tumor consisted of a smooth muscle actin and CD68-positive spindle cell population and a more abundant mononuclear inflammatory cell population, primarily composed of macrophages and T-lymphocytes. Inflammatory cells were the source of connective tissue growth factor and transforming growth factor-beta1 and tended to accumulate around nerves and blood vessels, as well as around residual pancreatic parenchymal elements, where an intense angiogenetic response was detected. Comparative genomic hybridization analysis of the tumor showed no chromosomal imbalances. Polymerase chain reaction-based analysis of T-cell receptor gamma gene rearrangement revealed an oligoclonal pattern. These findings suggest that the pathogenesis of aggressive cases of IPT could be related to the development of an intense and self-maintaining immune response, with the emergence of clonal populations of T-lymphocytes. The relation of the pancreatic IPT to autoimmune pancreatitis is emphasized.

Inflammatory myofibroblastic tumor (IMT) of the pancreas.J Hepatobiliary Pancreat Surg. 2002;9(1):116-9.

Inflammatory myofibroblastic tumor (IMT) is an uncommon mass lesion composed of a variety of inflammatory and other mesenchymal cells. Although IMT was originally reported in the lung, it is now recognized that IMT can occur in a variety of organs. The occurrence of IMT in the pancreas, however, is rare. Here, we report a case of IMT arising from the head of the pancreas in a 55-year-old man. He underwent pancreaticoduodenectomy, with the diagnosis of carcinoma of the pancreas; the pathological diagnosis of the tumor was IMT. By referring to previously reported cases, we conclude that, in the management of IMT in the pancreas, surgical excision is the primary choice, in order to obtain a definitive diagnosis as well as to relieve symptoms, and strict follow-up after surgery is required.

Inflammatory myofibroblastic tumor of the pancreas with regional lymph node involvement. Pathologe. 2002;23(2):161-6.

Inflammatory myofibroblastic tumors (IMT) can be found in virtually any location of the human body. Histologically a mesenchymal aspect predominates and makes these mostly benign tumors apt to be erroneously diagnosed as a soft tissue sarcoma. Cases showing infiltrative growth and local recurrence further complicate the assessment. Localization of an IMT in the pancreas is extremely rare. Clinical investigations regularly lead to the putative diagnosis of a malignant tumor and only subsequent histological examination can establish the correct tumor classification. We present the case of a 62-year-old woman with IMT of the pancreas. Evidence of lymph node involvement has not yet been reported in this setting.

Inflammatory pseudotumour (inflammatory myofibroblastic tumour) of the pancreas: a report of six cases associated with obliterative phlebitis.Histopathology. 2001 Feb;38(2):105-10.

AIMS: To describe in detail an uncommon pancreatic condition, which generally presents with cholestasis and a mass lesion suspicious of malignancy, and which is characterized histologically by proliferation of fibrous tissue with associated moderate or marked inflammation, as well as obliterative phlebitis. METHODS AND RESULTS: Out of a consecutive series of 23 pancreaticoduodenectomy specimens which on histological evaluation were found to contain no malignant tumour, six cases characterized by the features mentioned above were identified and investigated further. Poor circumscription, firm consistence, histology of dense sclerosis with scattered round cell infiltrates and associated obliterative phlebitis and often perineural accentuation of inflammation were the distinguishing features. On the basis of available histological evidence, the term inflammatory pseudotumour perhaps remains the term best suited to designate this entity, since it sums up its two most distinctive features. However, the possibility that this lesion is in fact a neoplastic process with reactive inflammation (inflammatory myofibroblastic tumour) cannot be ruled out on the basis of the histology, and remains a serious consideration in view of the proven neoplastic nature of lesions with very similar histology arising elsewhere in the body. Importantly, none of the pancreatic lesions reported here recurred or progressed (five informative cases, median follow-up time 70 months). CONCLUSIONS: Inflammatory pseudotumour (inflammatory myofibroblastic tumour) of the pancreas may closely mimic pancreatic adenocarcinoma clinically and radiologically.