IgG4-Related Inflammatory Pseudotumor Involving the Clivus: A Case Report and Literature Review

IgG4-related inflammatory pseudotumors are very uncommon and are characterized histologically by the presence of inflammatory swellings with increasing IgG4-positive plasma cells and lymphocytes infiltrating the tissues. As reports of intracranial IgG4-related pseudotumors are very rare, we report a case of an IgG4-related inflammatory pseudotumor involving the clivus mimicking meningioma. A 46-year-old male presented with intermittent headache for 2 years and a sudden onset of dysphagia and dysphonia of 7 days' duration along with lower limb weakness. Enhanced magnetic resonance imaging (MRI) of the skull base revealed an isointense signal on T1- and T2-weighted images from an enhanced mass located at the middle of the upper clivus region, for which a meningioma was highly suspected. Then, an endoscopic transsphenoidal approach was adopted and the lesion was partially resected, as the subdural extra-axial lesion was found to be very tough and firm, exhibiting fibrous scarring attaching to the brain stem and basal artery. After the surgery, brain stem and posterior cranial nerve decompression was achieved, and the patient's symptoms, such as dysphagia, dysphonia and lower limb weakness, improved. Pathological findings showed many IgG4-positive plasma cells and lymphocytes surrounded by collagen-rich fibers. The patient was sent to the rheumatology department for further glucocorticoids after the diagnosis of an IgG4-related inflammatory pseudotumor was made. This case highlights the importance of considering IgG4-related inflammatory pseudotumors as a differential diagnosis in patients with lesions involving the clivus presenting with a sudden onset of symptoms of dysphagia and dysphonia along with lower limb weakness when other more threatening causes have been excluded. IgG4-related inflammatory pseudotumors are etiologically enigmatic and unpredictable, and total resection might not be warranted. Glucocorticoids are usually the first line of treatment after diagnosis.

Implant failure in bilateral metal-on-metal hip resurfacing arthroplasties: a clinical and pathological study

Metal-on-metal hip resurfacing arthroplasties (MoMHRAs) have a high failure rate due to pseudotumour formation. It is not certain whether pseudotumours in bilateral MoMHRAs form on the basis of an adverse reaction to metal debris (ARMD) that is entirely due to a local innate and adaptive immune response to Cobalt-Chrome (Co-Cr) wear particles. To determine if there is a systemic component to ARMD in bilateral MoMHRAs, we examined the histology of ARMD in unilateral and bilateral MoMHRAs revised for pseudotumour and determined whether implant survival differed between these two groups. Periprosthetic tissue specimens from 119 hips revised for pseudotumour were examined. These were derived from 109 patients including 10 patients with bilateral MoMHRAs and 99 with sunilateral MoMHRAs including a cohort of 20 patients with bilateral MoMHRAs that had undergone only one MoMHRA revision for pseudotumour. The mean time to revision for pseudotumour of unilateral and bilateral MoMHRAs was determined. The histology of periprosthetic tissue was examined for evidence of the innate and adaptive immune response and scored semi-quantitatively. There was no significant difference in histological features of the innate / adaptive response between Group 1 bilateral pseudotumours and Group 2 and Group 3 unilateral pseudotumours. Histological features, including ALVAL scores, were similar in the periprosthetic tissues of right and left hips in Group 1 bilateral MoMHRAs. The mean time to first revision for pseudotumour of bilateral MoMHRAs (6.59 years) was not decreased compared with unilateral MoMHRAs (5.66 years) or bilateral MoMHRAs that had only one revision (7.05 years). Right and left hip pseudotumours in bilateral MoMHRAs exhibit similar histological features of the innate and adaptive immune response. Mean implant survival is not decreased in bilateral compared with unilateral MoMHRA cases. The findings suggest that pseudotumour formation is due more to a local than a systemic innate /adaptive immune response to components of metal wear.

Frank Stinchfield Award: Identification of the At-risk Genotype for Development of Pseudotumors Around Metal-on-metal THAs

BACKGROUND

Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive.

QUESTIONS/PURPOSES

The aim of this research, as a clinical-genotype correlation analysis, was to identify specific alleles (genes) associated with the development of ALTRs in patients with in situ MoM THAs.

METHODS

A case-control study of patients who received a large-head, primary MoM THA between 2005 and 2008 was performed with a minimum followup of 5 years. Twenty-six patients who had undergone revision of a primary MoM THA secondary to symptomatic ALTRs were recruited. The mean timeframe from primary MoM THA to symptomatic revision was 5.5 years (range, 1-10 years). Twenty-eight control subjects were randomly selected asymptomatic patients with no evidence of ALTRs on protocol-specific screening. Baseline demographics and high-resolution genotype (human leukocyte antigen [HLA] Class II) were collected for all patients. Cohorts were similar with respect to age at the time of primary MoM THA (mean, 54.8 versus 54.9 years, p = 0.95) and serum cobalt (mean, 5.5 versus 8.5 μg/L, p = 0.09) and chromium concentrations (mean, 2.9 versus 4.2 μg/L, p = 0.27). The association between genotype and revision surgery secondary to ALTRs was determined with gender as a covariate.

RESULTS

The prevalence of the risk genotype was 30% (16 of 54) among the entire cohort. Adjusting for sex, the odds of revision were 6.1 times greater among patients with the risk genotype present than among patients without (95% confidence interval [CI], 1.5-25.4; p = 0.01). Among females, the specificity of the risk genotype was 1.0 (95% CIexact, 0.5-1.0; pexact = 0.03), and for males, it was 0.8 (95% CIexact, 0.6-0.9; pexact < 0.01).

CONCLUSIONS

The findings of this study suggest that, among patients with a primary MoM THA, allelic variation within the HLA Class II loci may be a strong, independent risk factor associated with the need for subsequent revision surgery secondary to pseudotumor formation.

CLINICAL RELEVANCE

Given the hypothesis-generating nature of this novel undertaking, confirmatory prospective clinical studies are required to further elucidate this correlation and to explore the clinical utility of targeted genetic screening in this specific population. This research may, however, represent a key missing piece in the puzzle that is metal ion-induced pseudotumor formation.

Role of MR in the differentiation of IgG4-related from non-IgG4-related hepatic inflammatory pseudotumor

BACKGROUND

Hepatic inflammatory pseudotumor (IPT) is classified into 2 types based on IgG4 stain: IgG4-related and non-IgG4-related; the two types differ not only in their pathological characteristics, but also in the clinical features. This study aimed to investigate the MR character of hepatic IPT, and differentiate the IgG4-related IPT from the non-IgG4-related IPT.

METHODS

Twenty-five patients with 27 histologically proven hepatic IPTs were retrospectively analyzed. Ten lesions were diagnosed as IgG4-related IPT, and the other 17 as non-IgG4-related IPT. The MR signal features on T1, T2-weighted, dynamic-enhanced, and diffusion-weighted imaging were evaluated and compared.

RESULTS

The dominant lesions were subcapsularly distributed (n=17, 63.0%) with clear boundary (n=20, 74.1%), and showed progressive enhancement pattern (n=21, 77.8%) with diffuse homogeneous (n=12, 44.4%) or heterogeneous (n=8, 29.6%) hyperintensity, accompanied by delayed capsule-like enhancement (n=17, 63.0%) and central nonenhanced areas (n=18, 66.7%). Morphological features (P>0.05) were not sufficient to differentiate IgG4-related IPT from non-IgG4-related IPT; the wash-out pattern was only found in 2 IgG4-related IPT, while the progressive enhancement pattern was more common in the non-IgG4-related lesions (n=16) (P=0.022). During portal and delayed phases, iso-/hypoenhanced lesions were only seen in 3 IgG4-related IPT, and circular-enhanced lesions (n=5) existed exceptionally in the non-IgG4-related group with significant differences (P=0.029 and 0.027). Most IgG4-related IPTs had lower apparent diffusion coefficient compared with the liver parenchyma (n=6), while most non-IgG4-related IPTs had higher apparent diffusion coefficient value (n=13) (P=0.046).

CONCLUSIONS

Although MR images of hepatic IPT have certain characteristics, they are not enough to differentiate IgG4-related IPT from non-IgG4-related IPT. The enhancement pattern, signal features on portal and delayed phases, and the apparent diffusion coefficient value of the lesion may be helpful for the diagnosis.

[Inflammatory pseudotumor of the spleen: A case report]

Since the publication of the first two cases in 1984 by Cotelingam and Jaffe, a hundred of cases were published concerning the splenic inflammatory pseudotumor. The inflammatory pseudotumor is a benign lesion of unknown etiology. It forms a group of solid mesenchymal tumors occurring in different organs mainly in adulthood with female predominance. Symptomatic patients most often manifest fever, abdominal pain and splenomegaly. A substantial proportion of the inflammatory pseudotumors of the spleen are discovered incidentally. In this article we report a case of inflammatory pseudotumor in a 41-year-old male patient. The diagnosis of inflammatory pseudotumor of the spleen is made up by the histological and immunohistochemical examination.

IgG4-related plasma cell granuloma of the maxillary sinus: A report of 2 cases

We report 2 rare cases of IgG4-related plasma cell granuloma of the maxillary sinus. Histologically, both lesions were characterized by severe lymphoplasmacytic infiltration. In 1 case, fibrous sclerosis and obliterative arteritis were observed. Immunohistochemical study demonstrated that IgG4-positive cells comprised more than 40% of the IgG-positive plasma cells. Moreover, the serum IgG4 level was elevated in both cases. A good responsiveness to steroid therapy has been seen in IgG4-related disease. From a therapeutic perspective, it is important to recognize IgG4-related plasma cell granuloma.

Plasma Cell Granuloma: An Entity within the Spectrum of IgG4-Related Disease

Plasma cell granuloma (PCG) is a relatively rare, mass-forming lesion comprised of polyclonal plasma cells set in a background of storiform fibrosis and spindle cell proliferation. While uncommon, this lesion may occur within any site and should be included in the list of differential diagnoses for plasma cell neoplasms. As this entity can be mistaken for a plasma cell neoplasm, surgical pathologists should consider ancillary studies to assess clonality of plasma cell proliferations, especially during intraoperative consultation.Although the etiology of these lesions is unclear, recent literature and immunohistochemical stains performed on our own cases suggest that PCG falls within the spectrum of IgG4 related diseases, which would have significant clinical significance impacting treatment and the potential for associated disease at distant body sites. We present two cases of head and neck PCG encountered at a tertiary academic medical center with immunohistochemical staining demonstrating increased IgG4-secreting plasma cells.

Fast growing pseudotumour in a hairdresser after metal-on-metal hip resurfacing: a case report

A 44-year-old female hairdresser who underwent metal-on-metal hip resurfacing (MOMHR) for hip osteoarthritis developed a benign pelvic pseudotumour. Elevated levels of chromium and cobalt ions were detected in the blood. Patch testing after pseudotumor formation, showed positive skin reactions to cobalt and nickel. Marked hypereosinophilia was noted, as well as the presence of eosinophils in the pseudotumor mass. A revision to a ceramic-on-ceramic implant was performed. Radiographs showed no implant loosening or bone resorption. We hypothesized that a steep cup positioning as well as hypersensitivity response to the metal nanoparticles and ion release may have induced pseudotumour development. Currently there is no evidence that negative patch testing reduces the probability to develop an adverse reaction to metal debris therefore we suggest to carefully investigate patient medical history regarding occupation exposure and daily contact with jewellery, beauty and cleaning products before implanting MOMHR. The main challenge is to identify a sensitive patient candidate to MOMHR never suspected to be.

Immunoglobulin G4-related gastrointestinal diseases, are they immunoglobulin G4-related diseases?

In immunoglobulin G4 (IgG4)-related disease (RD), organ enlargement or nodular lesions consisting of abundant infiltration of lymphocytes and IgG4-positive plasma cells and fibrosis are seen in various organs. Although infiltration of many IgG4-positive plasma cells is detected in the gastric and colonic mucosa and major duodenal papilla of patients with autoimmune pancreatitis, it cannot be diagnosed as a gastrointestinal lesion involved in IgG4-RD, because none of the following is observed in these lesions: a mass-like formation; dense fibrosis; or obliterative phlebitis. Based on our review of the literature, there appear to be two types of IgG4-related gastrointestinal disease. One is a gastrointestinal lesion showing marked thickening of the wall of the esophagus and stomach, consisting of dense fibrosis with abundant infiltration of IgG4-positive plasma cells, which usually show submucosal spreading. The other is an IgG4-related pseudotumor occurring in gastrointestinal regions such as the stomach, colon, and major duodenal papilla, showing polypoid or mass-like lesions. Most solitary IgG4-related gastrointestinal lesions that are not associated with other IgG4-RD appear to be difficult to diagnose. It is of utmost importance to rule out malignancy. However, these lesions may respond to steroid therapy. To avoid unnecessary resection, IgG4-related gastrointestinal diseases should be considered in the differential diagnosis.

IgG4-related sclerosing disease: an emerging entity frequently misdiagnosed

IgG4-related sclerosing disease, a multiorgan system disease that has been identified in the last 10 years, is a fibroinflammatory condition with a marked propensity to manifest itself as mass forming lesions characterized by three main histological features (sclerosis, obliterative phlebitis and lymphoplasmacytic infiltrate) and by the presence of abundant IgG4+ plasma cells, frequent elevation of serum IgG4 and a dramatic initial response to steroid therapy. The aim of this mini-review is to increase the capacity to identify the characteristic features of IgG4-related sclerosing disease in specific organs and in two newly proposed entities (urethral caruncle and paratesticular fibrous pseudotumor) using biopsy specimens and methods of counting IgG4. In addition we examine the relationship between IgG4-related sclerosing disease and malignancy. In fact, an increased ability to recognize the characteristic features of IgG4-related sclerosing disease would play an extremely important role in avoiding unnecessary surgery in favor of initiating corticosteroid therapy.

Inflammatory angiomyolipoma of the liver: an unusual case suggesting relationship to IgG4-related pseudotumor

Hepatic angiomyolipoma (AML) is rare. Based on its wide histomorphological range, several distinctive histological variants have been delineated. However, hepatic AML displaying predominantly or exclusively inflammatory pattern closely mimicking inflammatory pseudotumor (IPT) is exceptionally rare with only 7 cases reported so far. We herein describe a new case of hepatic inflammatory AML in a 51-year-old woman who presented with unexplained constitutional symptoms suggesting an infectious disease. A liver mass was detected during imaging examination and resected (4.3 cm in maximum diameter). The patient's symptoms resolved completely after surgery. Currently, she is alive and well 7 years after surgery. She has no evidence of other organ manifestations of IgG4-related systemic disease. The tumor displayed a pure IPT-like histological pattern with dense infiltrates of plasma cells, lymphocytes and histiocytes admixed with scattered few adipocytes, irregularly distributed thick-walled vessels (some of them showed obliterative phlebitis) as well as aggregates and fascicles of histiocytoid and spindle-shaped myoid cells that were immunoreactive for HMB45 and Melan A with focal expression of alpha smooth muscle actin. Lesional cells were negative for desmin, protein S100, CD21, CD23, CD15, CD30, HepPar-1, pankeratin (KL-1), ALK1, and EBV in situ hybridization (EBER). The surrounding liver parenchyma showed striking lymphoplasmacytic non-destructive pericholangitis. Numerous scattered and aggregated IgG4 positive plasma cells were seen within the mass and in the peritumoral inflammatory lesions (mean, 37 cells/HPF; IgG4: IgG ratio = 28%). To our knowledge, this is the first report of hepatic inflammatory AML closely resembling IgG4-related IPT of the liver. A possible role for IgG4 seems likely to explain the peculiar histological features and the unusual clinical presentation in this case.

IgG4-related disease

IgG4-related disease (IgG4-RD) is considered a fibro-inflammatory condition with a marked propensity to form mass forming lesions, characterized by a dense lymphoplasmacytic infiltrate, the presence of abundant IgG4+ plasma cells, frequent elevation of serum IgG4 and a dramatic initial response to glucocorticoid. Nowadays, IgG4-RD has been described in almost every organ system: the pancreatobiliary tract, liver, salivary glands, nasopharynx, bone marrow, lacrimal gland, extra-ocular muscles and retrobulbar space, kidneys, lungs, lymph nodes, meninges, aorta and arteries, skin, breast, prostate, thyroid gland and pericardium. Although the common diagnostic features of all these regional involvements cannot be defined with certainty, and slight differences have been noted in different organs, many histopathological features are shared. Consensus has not yet been reached regarding criteria that have to be fulfilled for a new IgG4-RD. The proposed criteria include appropriate clinical and histopathological findings, presence of abundant tissue-infiltrating IgG4+ plasma cells, high serum IgG4 concentrations, response to steroid therapy, other autoimmune diseases or other organ involvement. The two hallmark features for diagnosis are histopathological characteristics and the presence of infiltrating IgG4+ plasma cells. In this review, we will focus on the histopathological features of IgG4-RD in specific organs and discuss the relationship with inflammatory pseudotumour and malignancy, IgG4 counting methods, and diagnosis using biopsy specimens. IgG4-related disease (IgG4-RD) is a multi-organ system disease that has been recognized in the last 10 years. IgG4-RD has a marked propensity to present as mass-forming lesions. The two hallmark features for diagnosis are histopathological characteristics and the presence of infiltrating IgG4+ plasma cells. Correct identification is crucial to avoid unnecessary major surgical procedures and initiate corticosteroid therapy.

A case of Mikulicz's disease complicated by malignant lymphoma: a postmortem histopathological finding

A 66-year-old Japanese man with an 11-year history of Mikulicz's disease (MD) received continuous corticosteroid administration. At age 58, a left renal pelvic mass was identified and diagnosed as an IgG4-related inflammatory pseudotumor. The patient underwent an operation to remove the tumor. Subsequently, he contracted repeated pulmonary infections and eventually died of severe gastrointestinal bleeding. Autopsy revealed systemic lymph node swelling and infiltration in some organs, and diffuse large B-cell lymphoma (DLBCL) was diagnosed. These findings suggest that an IgG4-related disease can be causally related to the development of malignant lymphoma through the occurrence of mucosa-associated lymphoid tissue lymphoma.

Pseudotumors due to IgG4 immune-complex tubulointerstitial nephritis associated with autoimmune pancreatocentric disease

Autoimmune pancreatitis (AIP) is a mass-forming chronic fibroinflammatory condition centered on the pancreatobiliary system and characterized by predominant immunoglobulin G4 (IgG4)-positive plasma cells. Recent reports have brought to light the multiorgan involvement of this disease. We describe a series of 5 cases of tubulointerstitial nephritis (TIN) associated with AIP and characterize the clinical, pathologic, ultrastructural, and immunopathologic features of TIN. The specimens consisted of 4 biopsies and 1 nephrectomy. The average patient age was 64 years (range 45 to 78) and the male to female ratio was 4:1. All had histologic and/or clinical and radiographic evidence of AIP, mass-forming sclerosing cholangitis, or both. The clinical impression in 4 patients was a renal mass or vasculitis. Two patients had renal insufficiency. Histologic preparations revealed a dense tubulointerstitial lymphoplasmacytic infiltrate. Eosinophils were often numerous. Tubulitis and tubular injury were present, along with tubular atrophy with focally thickened tubular basement membranes (TBMs). The histologic appearance ranged from a cellular, inflammatory pattern without tubular atrophy to a striking expansive interstitial fibrosis with tubular destruction. The nephrectomy specimen demonstrated a masslike nodular pattern of inflammation with normal renal tissue elsewhere. Glomeruli were uninvolved. By immunohistochemistry or immunofluorescence, numerous plasma cells in the infiltrate were positive for IgG4. TBM granular IgG deposits, predominantly of the IgG4 subclass, were detected in 4 of 5 cases by either immunofluorescence or immunohistochemistry. By electron microscopy, corresponding amorphous electron-dense deposits were present in the TBM in these cases. This type of TIN, typically characterized by a masslike lesion consisting of a lymphoplasmacytic infiltrate with eosinophils and prominent IgG4-positive plasma cells and immune-complex deposits in the TBM, may be part of a systemic IgG4-related disease, which we term "IgG4-associated immune complex Multiorgan Autoimmune Disease" (IMAD).

Pathological classification of hepatic inflammatory pseudotumor with respect to IgG4-related disease

Recently, much attention has focused on IgG4-related disease, which is characterized by abundant IgG4-positive plasma cell infiltration and high serum IgG4 levels. IgG4-related disease sometimes manifests as tumorous lesions, and its relationship to inflammatory pseudotumor has been suggested. In this study, we examined clinicopathological features of a total of 16 cases of hepatic inflammatory pseudotumor (11 men and 5 women with an average age of 67 years) with respect to IgG4-related disease. The tumors could be pathologically classified into two types: fibrohistiocytic (10 cases) and lymphoplasmacytic (6 cases). Fibrohistiocytic inflammatory pseudotumors were characterized by xanthogranulomatous inflammation, multinucleated giant cells, and neutrophilic infiltration, and mostly occurred in the peripheral hepatic parenchyma as mass-forming lesions. In contrast, lymphoplasmacytic inflammatory pseudotumors showed diffuse lymphoplasmacytic infiltration and prominent eosinophilic infiltration, and were all found around the hepatic hilum. In addition, venous occlusion with little inflammation and cholangitis without periductal fibrosis were frequently observed in the fibrohistiocytic type, whereas obliterative phlebitis and cholangitis with periductal fibrosis were common features of the lymphoplasmacytic type. Interestingly, IgG4-positive plasma cells were significantly more numerous in the lymphoplasmacytic than fibrohistiocytic type. However, two of the fibrohistiocytic inflammatory pseudotumors had relatively many IgG4-positive plasma cells. In conclusion, hepatic inflammatory pseudotumor could be classified into two types based on clinicopathological characteristics. The lymphoplasmacytic type is unique, and could belong to the so-called IgG4-related diseases. In contrast, the fibrohistiocytic type might still be a heterogeneous group of disorders. This latter type seems pathologically different from IgG4-related disease, although cases with relatively abundant IgG4-positive plasma cells should be differentiated from IgG4-related disease with secondary histopathologic modifications.

Inflammatory pseudotumors of the pancreas and liver with infiltration of IgG4-positive plasma cells

Recently, it has been reported that autoimmune pancreatitis (AIP) can be complicated with various extrapancreatic lesions. Here, we report a very rare case of pancreatic and hepatic inflammatory pseudotumor (IPT) with the infiltration of IgG4-positive plasmacytes. The patient showed pancreatic and hepatic masses with elevated levels of serum IgG4. Endoscopic retrograde cholangiopancreatography revealed narrowing of the intrapancreatic bile duct. Fluorine-18fluorodeoxyglucose positron emission tomography suggested pancreatic cancer with hepatic metastasis. Histopathologic findings showed fibrosis and infiltration of IgG4-positive plasmacytes, suggesting IPT. The present case suggests a possible common mechanism in the development of AIP and IPT of the liver.

Adult-onset asthma and periocular xanthogranulomas in a patient with lymphoplasmacytic sclerosing pancreatitis

The clinical syndrome of adult-onset asthma and periocular xanthogranulomas represents a rare systemic autoimmune disorder that has not been previously associated with autoimmune pancreatitis. Herein, we describe the case report of a 61-year-old man with the unique clinical association of adult-onset asthma, atopy, and periocular xanthogranulomas, who had previously been diagnosed with lymphoplasmacytic sclerosing pancreatitis. We have previously reported the case of a patient with lymphoplasmacytic sclerosing pancreatitis that developed postoperative inflammatory pseudotumor of the orbit. These unique, extrapancreatic, ocular manifestations of this disease add to the published observations that it is a systemic disorder with the potential for multiorgan involvement that may have a spectrum of clinical manifestations that includes adult-onset asthma and periocular xanthogranulomas.

Effects of transforming growth factor-beta in the development of inflammatory pseudotumour-like lesions in a murine model

Alterations in transforming growth factor (TGF)-beta signalling have been frequently implicated in human cancer, and an important mechanism underlying its pro-oncogenic nature is suppression of the host antitumour immune response. Considering the immunosuppressive effect of TGF-beta, we asked whether human tumour cells, known to secrete TGF-beta in culture, would survive and grow when implanted into the peritoneal cavity of immunocompetent mice. Therefore, we developed a xenogeneic model where mice were intraperitoneally (i.p.) injected with a TGF-beta-secreting human colorectal adenocarcinoma cell line, LISP-A10. Although animals did not develop macroscopic tumours, the recovery and isolation of human tumour cells was achieved when an inflammatory environment was locally induced by the administration of complete Freund's adjuvant (CFA). This procedure significantly increased TGF-beta concentrations in the peritoneal fluid and was accompanied by impaired activation of the host-specific immune response against LISP-A10 cells. Furthermore, inflammatory lesions resembling human inflammatory pseudotumours (IPTs) were observed on the surface of i.p. organs. These lesions could be induced by either injection of LISP-A10 cells, cells-conditioned medium or recombinant TGF-beta but only after administration of CFA. In addition, host cyclooxygenase-2 and kinin receptors played an important role in the induction of TGF-beta-mediated IPT-like lesions in our experimental model.

Inflammatory pseudotumor of the breast in a patient with a high serum IgG4 level: histologic similarity to sclerosing pancreatitis

The association between IgG4 and inflammatory pseudotumor was first reported with regard to pancreatic pseudotumor, which is well known as sclerosing pancreatitis or autoimmune pancreatitis. In addition, there is increasing evidence that IgG4 is also involved in inflammatory pseudotumor of the extrapancreatic tissue. In this report, we present a case of IgG4-related inflammatory pseudotumor of the breast. A 46-year-old woman presented with an induration in the left breast. Radiologic examination revealed an ill-circumscribed mass measuring 1.6 cm in diameter in the left breast. Breast cancer could not be ruled out radiologically, and excision biopsy was performed for a definite diagnosis. Histologically, this nodule was composed of an irregular proliferation of stromal cells associated with severe lymphoplasmacytic infiltration, obliterative phlebitis, and eosinophils. No atypical feature regarding the stromal cells or lymphocytes was observed. Furthermore, many plasma cells within the lesion were immunohistochemically positive for IgG4, and the serum IgG4 concentration of this patient was elevated on postoperative examination. This case suggests that inflammatory pseudotumor of the breast has a pathogenetic process similar to that of sclerosing pancreatitis. IgG4 might become a useful marker for inflammatory pseudotumor of the breast, and it might benefit from steroid therapy, as does sclerosing pancreatitis.

Autoimmune pancreatitis: pathological findings

In recent years, autoimmune pancreatitis has been established as a special type of chronic pancreatitis. It is characterized by its histopathological and immunological features. The morphological hallmarks are periductal infiltration by lymphocytes and plasma cells and granulocytic epithelial lesions with consequent destruction of the duct epithelium and venulitis. Autoimmune pancreatitis has therefore also been called lymphoplasmacytic sclerosing pancreatitis, duct-destructive chronic pancreatitis, or sclerosing pancreatitis. Autoimmune pancreatitis most commonly involves the head of the pancreas and the distal bile duct. Occasionally, masses are formed and it has been described as an inflammatory myofibroblastic tumor.

Oligoclonal T-cell populations in an inflammatory pseudotumor of the pancreas possibly related to autoimmune pancreatitis: an immunohistochemical and molecular analysis

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.

Plasma cell granuloma in cyclosporine-induced gingival overgrowth: a report of two cases with immunohistochemical positivity of interleukin-6 and phospholipase C-gamma1

We report two cases of gingival plasma cell granuloma in a 34-yr-old and 40-yr-old two male renal transplant recipients with cyclosporine A (CsA)-induced gingival overgrowth (GO). Histologically, these lesions were composed of mature plasma cells, showing polyclonality for both lambda and kappa light chains and fibrovascular connective tissue stroma. In addition to the fact that CsA-induced plasma cell granuloma is rare, the salient features of our cases were the secretion of interleukin-6 and overexpression of phospholipase C- gamma 1 of the tumor cells, which may explain the mechanisms of CsA- induced GO.

Diagnosis of inflammatory pseudotumor of the liver

Inflammatory pseudotumor (IPT) is a rare benign tumor of unknown origin, it has the appearance of a malignant tumor but has a benign histology and clinical course. Therefore, we studied five patients with IPT of the liver to determine what examination can aid in its diagnosis. Five cases of inflammatory pseudotumor of the liver were analyzed. All patients were examined by echography, computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiography (ERC) and angiography to diagnose the liver tumor. In all patients echography and CT scan showed a similar appearance while MRI showed a variable pattern. In two patients ERC showed a stenotic image of intra-hepatic bile ducts. In the angiographic study, the arterial phase in three patients showed a hypervascular tumor and in one patient, a hypovascular tumor. Vascular abnormality was presented in one patient. Similarly, portography in four patients showed some abnormality. We performed ultrasonography-guided percutaneous needle biopsy in two patients in order to diagnose IPT. Histological examinations of two patients were consistent with IPT. The other three patients underwent surgical treatment for a cholangiocellular carcinoma or abscess. It is difficult to diagnose IPT of the liver exclusively with an image examination. Ultrasonography-guided percutaneous liver biopsy should be performed in order to diagnose IPT by histology.

Splenic inflammatory myofibroblastic tumor (inflammatory pseudotumor): a clinicopathologic and immunophenotypic study of 12 cases

CONTEXT

Inflammatory pseudotumor is an uncommon and enigmatic lesion. The spindle cells found in this tumor have features of myofibroblasts. Because of the indefinite relationship of these lesions with inflammatory fibrosarcoma and their indefinite biologic behavior, inflammatory pseudotumor is currently classified as inflammatory myofibroblastic tumor (IMT). To date, only case reports or small series have been published on these tumors, which are primary in the spleen.

DESIGN

In this study, we describe the clinical, morphologic, and immunophenotypic findings of 12 cases of splenic IMT and examine their relationship to Epstein-Barr virus (EBV).

RESULTS

The patients included 8 women and 3 men, ranging from 19 to 77 years of age (mean, 53 years; median, 60 years). Demographic data were unavailable for 1 patient. Patients generally presented with abdominal pain (n = 5) and fever (n = 4). Associated lesions included renal cell carcinoma (n = 2), colonic adenocarcinoma (n = 1), and cholecystitis (n = 1). All tumors were composed of a bland spindle cell proliferation in association with a variable mixed inflammatory component. There were 2 growth patterns, namely, a cellular spindle cell pattern and a hypocellular fibrous pattern. An immunohistochemical panel confirmed the myofibroblastic nature of the spindle cells. The spindle cells of 2 cases were immunoreactive for EBV latent membrane protein 1, whereas 6 of 10 cases were positive for EBV-encoded RNA using in situ hybridization. Follow-up was available for 8 patients; 6 were alive with no evidence of recurrence and 2 were dead of other causes.

CONCLUSION

Splenic IMTs are uncommon lesions that can be distinguished from other conditions using a combination of clinical, histologic, and immunophenotypic findings. Epstein-Barr virus may play a role in the pathogenesis of splenic IMT, and there may be an association of splenic IMT with concomitant disease or malignancy. Most splenic IMTs have an excellent long-term prognosis.

Crystal-storing histiocytosis: a disorder occurring in plasmacytic tumors expressing immunoglobulin kappa light chain

Intracellular immunoglobulin crystal formation within plasma cells is an uncommon finding in multiple myeloma and other lymphoplasmacytic tumors. We present 12 cases of plasmacytic tumors with prominent crystal formation, including myeloma (5 cases), lymphoplasmacytic lymphoma (6 cases), and a nonneoplastic plasma cell proliferation. In all cases, crystal formation was associated with the proliferation of variable numbers of histiocytes containing similar inclusions. These cases showed a variety of appearances, sometimes obscuring the underlying plasma cell tumor and raising the differential diagnosis of a storage disorder, hemophagocytosis, or a mesenchymal lesion. In cases of lymphoplasmacytic lymphoma, patients typically presented with marked paraproteinemia and symptoms of hyperviscosity. Crystal-storing histiocytosis was not associated with other immunoglobulin deposition disorders, including amyloidosis, Mott cell tumors, or kappa-light chain deposition. In our cases and those previously reported, we found an overwhelming association of crystal-storing histiocytosis (CSH) with tumors expressing immunoglobulin kappa light chain with no consistent association with a particular heavy chain. These results suggest that CSH results from the ingestion of crystals produced by plasma cell tumors that either overproduce kappa light chain or express a structurally aberrant molecule. CSH persists in the marrow and other sites throughout the course of the disease and in our series was not highly associated with development of the adult Fanconi syndrome or rapid clinical deterioration.

A case of inflammatory pseudotumor of the liver causing elevated serum CA19-9 levels

Inflammatory pseudotumor of the liver is a rare lesion characterized by proliferating fibrovascular tissue admixed with inflammatory cells. A 50-yr-old Japanese man was hospitalized because of upper abdominal pain and high fever. Computed tomography revealed a poorly demarcated, low density mass in the left lobe of the liver, and abnormal laboratory findings included WBC 9340/mm3, CRP 10.5 mg/dl, and marked elevation of CA19-9 to 1167.9 U/ml. Endoscopic retrograde cholangiography showed irregularity of the intrahepatic bile duct of the left lateral segment, and the lateral segmental branches of the portal vein were not visualized on the venous phase of abdominal angiography. Ultrasound-guided liver biopsy was performed, but malignant disease, including intrahepatic cholangiocarcinoma, could not be completely ruled out. The patient underwent left hepatic lobectomy with lymph node dissection. Histopathological examination yielded a definitive diagnosis of inflammatory pseudotumor. The lesion was immunohistochemically stained for CA19-9 by the ABC method, and the biliary epithelium in severely inflamed portal canals was found to be positive. The markedly elevated preoperative level of CA 19-9 decreased to almost within the normal range and the patient remains well 2 yr 9 months after surgery, without any complications.

Gastric plasmacytoma coexistent with plasma cell granuloma in a patient with gastric cancer

We report a rare case of multiple gastric plasmacytomatous lesions at an early stage found incidentally in a stomach resected because of gastric cancer. The three lesions had different macroscopic features, showing depressed, submucosal, and nodular tumor-forming types. The smallest, a depressed lesion, produced IgG of the lambda and kappa types, and had a plasma-cell granuloma-like appearence, whereas the largest, a submucosal tumor, was formed by the monoclonal proliferation of atypical plasma cells containing IgA-kappa type immunoglobulin, and the nodular lesion exhibited histological features intermediate between those of the other two lesions. From their microscopic features and the profile of immunoglobulin production, we believe that these lesions may represent different stages in the possible course of development of plasmacytoma from the early stage of plasma cell granuloma. All three lesions were located far from the gastric carcinoma and it was unclear whether they had any causal relationship with it.

Inflammatory pseudotumors of lymph node origin show macrophage- derived spindle cells and lymphocyte-derived cytokine transcripts without evidence of T-cell receptor gene rearrangements. Implications for pathogenesis and classification as an idiopathic retroperitoneal fibrosis-like sclerosing immune reaction

Sclerosing pseudotumorous immune reactions of the retroperitoneum have been shown to consist of HLA-DR-positive spindle-shaped fibroblasts and macrophages that resemble fibroblasts, and in some instances they contain clonal populations of T lymphocytes not found in granulation tissue, keloids, nodular fasciitis, or fibromatoses. In patients who are iatrogenically immunosuppressed, circulating monocytes may be induced in vitro to transform into spindle-shaped macrophages, and secrete collagen after stimulation by conditioning medium from activated T lymphocytes. The authors investigated a series of five inflammatory pseudotumors (IPT) of lymph node origin for identification of spindle-shaped macrophages, T-cell receptor gene rearrangements, and lymphocyte-derived cytokine mRNA production. All cases of IPT demonstrated spindle-shaped macrophages resembling fibroblasts or myofibroblasts characterized by vimentin, CD45 (LCA), CD68 (KP1) or HAM-56, and HLA-DR(LN3) immunoreactivity and demonstrated production of procollagen-alpha1 (I) mRNA by in situ hybridization. Clonal T-cell receptor chain gene rearrangements were undetectable by polymerase chain reaction. Strong specific lymphocyte-derived interleukin-1beta and interleukin-6 mRNA cytokine transcripts were identified. Although all patients with IPT were managed with steroids and nonsteroidal anti-inflammatory medication, some had treatment-refractory disease. Because all-trans retinoic acid has been demonstrated to inhibit the in vitro transformation of monocytes into collagen-producing spindle-shaped macrophages ("neofibroblasts"), it may be of benefit for patients with IPT.

Inflammatory pseudotumor of the spleen. A clinicopathologic and immunophenotypic study of eight cases

We report the clinical, pathologic, and immunophenotypic findings of inflammatory pseudotumors of the spleen in eight patients. The primary importance of recognizing these uncommonly found lesions is to distinguish them from malignant lymphoma, which splenic inflammatory pseudotumors may mimic clinically and radiologically. Grossly, the splenic inflammatory pseudotumors in this study ranged from 0.5 to 11.5 cm. One case was multinodular, and seven lesions were solitary. In general, the size of the lesion correlated with the presence of symptoms. The smaller lesions were usually incidental findings, discovered as part of the workup of idiopathic thrombocytopenic purpura (three cases), during staging for Hodgkin's disease (one case), or at autopsy (one case). Microscopically, the lesions were composed of a variable mixture of inflammatory cells admixed within a spindle cell proliferation. Small, cytologically normal lymphocytes and plasma cells were constant features, in a variable mixture, with neutrophilic and eosinophilic leukocytes present in some cases. Coagulative necrosis was located centrally in six lesions; neutrophilic leukocytes were correlated with the presence of necrosis. The presence of necrosis did not correlate with the presence of symptoms. Immunohistochemical studies revealed that the small lymphocytes present were predominantly T cells. Histiocytes and polytypic plasma cells were also numerous, whereas B cells were infrequent. Inflammatory pseudotumors of the spleen are benign lesions. The clinical follow-up for the seven patients in this study who underwent splenectomy showed no evidence of recurrence or subsequent development of a hematopoietic neoplasm, with a median follow-up of 18 months (range, 3 to 135 months).

Inflammatory pseudotumor of the spleen. Report of a case with an immunohistochemical study

A 81-year-old Japanese man with a splenic inflammatory pseudotumor is described. The pseudotumor was unchanged in size after one year of observation. Macroscopically, the lesion was a firm well-circumscribed 5.5 x 5 x 5 cm mass showing a yellowish-white cut surface. Histologically, it was composed of abundant mixed inflammatory infiltrates, predominantly UCHL-1(+) T and L26(+) B lymphocytes, plasma cells containing various immunoglobulin subtypes, and S-100 protein(+), and lysozyme and NCA(+) histiocytes, with a sclerotic stroma. Small numbers of eosinophils, neutrophils and foamy macrophages were admixed. The patient has remained disease-free for 14 months after splenectomy. Only ten splenic inflammatory pseudotumors have been reported in the literature. This paper adds an additional case, together with details of immunohistochemical polyclonality of each inflammatory cell population, confirming that this disease is a nonspecific inflammatory change.

Neutrophil recruitment in the respiratory tract of a patient with plasma cell granuloma of the lung

A 69-year-old woman had plasma cell granuloma of the left middle lobe of the lung. Her symptoms and roentgenologic findings improved with antibiotic treatment. Before treatment, the number of neutrophils and NCA were markedly increased in BAL fluid obtained from the affected region of the left lung and moderately increased in BAL fluid obtained from the nonaffected region of the right lung. The number of neutrophils, the NCA as well as the contents of C5 and C5a des Arg (neutrophil chemotactic factors) in the BAL fluids from both these regions decreased during treatment. These findings suggest that plasma cell granuloma was due to chronic immune and inflammatory reactions in the lung, that neutrophils are involved in development of the symptoms and signs of this disease, and that neutrophil chemotactic factors, including complement-derived factors, are important in neutrophil recruitment at the lesion and in nonaffected parts of the lung.

[A case of plasma cell granuloma showing rapid growth and elevation of serum CEA]

A 67-year-old man was admitted with complaints of cough and hemosputum. Chest X-ray examination revealed enlargement of a coin lesion in the right upper lobe, which had been pointed out about one year previously and had been followed up. Although the histology of TBLB specimens and the cytology of sputum and materials showed no malignancy and chest CT showed calcification at the edge of the coin lesion, the mass shadow in the right upper lobe rapidly enlarged and the serum level of CEA gradually elevated. Therefore, it seemed to be impossible to neglect the possibility of lung cancer and right upper lobectomy was performed. The dissected specimen was diagnosed as plasma cell granuloma. Because the histology of the plasma cell granuloma is multifarious, TBLB shows various results. It is therefore difficult to diagnose such inflammatory tumors by TBLB. The increase of the mass shadow in size and the elevated serum level of CEA made it difficult to diagnose this case.

Plasma cell granuloma of the thyroid

Plasma cell infiltrates in the thyroid are rare. They may represent several processes, such as localized plasmacytoma, multiple myeloma, or plasma cell granuloma (PCG). It may be difficult to distinguish these disorders on the basis of morphologic features in sections stained with hematoxylin-eosin. All may be composed of mature plasma cells, without admixed macrophages or lymphocytes, that infiltrate the thyroid and adjacent connective tissue. The identification of the uncommon, but benign, PCG is facilitated by immunohistochemical staining to demonstrate an admixture of plasma cells with cytoplasmic kappa and lambda light chains. The polyclonal nature of the plasma cell infiltrate distinguishes PCG from neoplastic plasma cell proliferation.

[A case of so-called plasma cell granuloma of the stomach--demonstration of monoclonal immunoglobulin (IgM, K) in the plasma cells]

A patient with a surgically removed plasma cell granuloma of the stomach is reported. The patient was a 54-year-old male, the lesion was IIc-like on the anterior wall of the antrum. Histologically conspicuous features were marked thickening of the submucosa by fibrosis, hyperplastic lymph follicles and massive infiltration of mature plasma cells. However, immunohistochemical study using the PAP technique demonstrated the monoclonal nature of the infiltrating plasma cells which were positive for IgM, k. This is the fourth case of plasma cell granuloma reported in the literature, however, our findings also suggested that this might be an early stage of plasmacytoma.