Inflammatory pseudotumor of lymph nodes: clinicopathologic and immunohistological study of 11 Japanese cases

Clinicopathological differential diagnosis of IgG4-related disease: A historical overview and a proposal of the criteria for excluding mimickers of IgG4-related disease

IgG4-related disease (RD) is a relatively new entity, which was first proposed in 2001. Since then, clinical and pathological characteristics of the disease have been investigated. As IgG4-RD has been studied extensively, the diagnostic criteria for IgG4-RD of each organ and the comprehensive diagnostic criteria for IgG4-RD have also been developed. However, one of the biggest challenges in the field is distinguishing between IgG4-RD and mimickers, which show overlapping features with IgG4-RD. It is now known that some non-IgG4-RDs may meet the diagnostic criteria of IgG4-RD and can be misdiagnosed as IgG4-RD. However, accurate diagnosis is crucial, as the treatments for IgG4-RD and those for other diseases that may be misdiagnosed as IgG4-RD are different. This prompted us to create and propose comprehensive exclusion criteria for IgG4-RD. In this review, we have described the comprehensive exclusion criteria for IgG4-RD, with a historical overview of the disease. These exclusion criteria were recently created by the Research Program for Intractable Disease of the Ministry of Health, Labor, and Welfare of Japan, All Japan IgG4 team, to support correct and accurate diagnosis of IgG4-RD.

Inflammatory pseudotumor-like follicular dendritic cell sarcoma of the spleen: a report of six cases with increased IgG4-positive plasma cells

Inflammatory pseudotumor (IPT)-like follicular dendritic cell (FDC) sarcoma is a rare neoplasm typically occurring in the spleen or liver. We present six cases of EBV(+) IPT-like FDC sarcoma of the spleen among Koreans along with their clinicopathologic features and IHC results. Most patients presented with an asymptomatic, incidentally detected single splenic mass and were successfully managed by splenectomy alone. Concomitant disease was found in one case, showing EBV(+) gastric carcinoma with lymphoid-rich stroma. Histologic features showed fibro-inflammatory lesions that were often accompanied by necrosis and epithelioid histiocytic collection, which are barely distinguishable from IPT. Tumor cells did not frequently express conventional FDC markers, including CD21 (3/6 positive cases), clusterin (4/6), and D2-40 (2/6), but showed uniform positivity for smooth muscle actin (SMA). Noticeably, significant numbers of IgG4(+) plasma cells were found within all six tumors. We suggest that the diagnosis of IPT-like FDC sarcoma should be made by the application of a panel of FDC markers, and CD21 negativity or SMA positivity cannot be the criterion for exclusion of IPT-like FDC sarcoma. Relationship of IPT-like FDC sarcoma of the spleen and IgG4-related sclerosing disease should be investigated in further studies.

IgG4-Related Lymphadenopathy

Lymphadenopathy is frequently observed in patients with immunoglobulin G4-related disease (IgG4-RD) and sometimes appears as the first manifestation of the disease. The diagnosis of IgG4-related lymphadenopathy is complicated owing to a great histological diversity, with at least 5 histological subtypes. Indeed, lymph node biopsy may be performed under the suspicion that the lymphadenopathy is a malignant lymphoma or other lymphoproliferative disorder. The diagnosis of IgG4-RD is characterized by both elevated serum IgG4 (>135 mg/dL) and histopathological features, including a dense lymphoplasmacytic infiltrate rich in IgG4(+) plasma cells (IgG4(+)/IgG(+) plasma cell ratio >40%). However, patients with hyper-interleukin (IL-) 6 syndromes such as multicentric Castleman's disease, rheumatoid arthritis, and other immune-mediated conditions frequently show lymph node involvement and often fulfill the diagnostic criteria for IgG4-RD. Owing to these factors, IgG4-RD cannot be differentiated from hyper-IL-6 syndromes on the basis of histological findings alone. Laboratory analyses are crucial to differentiate between the 2 diseases. Hyper-IL-6 syndromes are characterized by elevated serum levels of IgG, IgA, IgM, and C-reactive protein (CRP); thrombocytosis; anemia; hypoalbuminemia; hypocholesterolemia. In contrast, IgG4-RD does not share any of these characteristics. Therefore, the diagnosis of IgG4-RD requires not only pathological findings but also clinical and laboratory analyses.

Primary IgG4-related lymphadenopathy with prominent granulomatous inflammation and reactivation of Epstein-Barr virus

We report a unique case of primary IgG4-related lymphadenopathy showing prominent granulomatous inflammation and Epstein-Barr virus (EBV) reactivation. Involved lymph nodes showed an expanded interfollicular zone with prominent granulomatous inflammation, including a predominance of epithelioid macrophages and occasional Langhans multinucleated giant cells. Bundles of spindle cells were also observed. Intermingled with the granulomatous inflammation were numerous mature plasma cells, eosinophils, and neutrophils. The percentage of IgG4+/IgG+ plasma cells was markedly elevated (70%), along with raised serum IgG4 levels. The plasma cells did not show immunoglobulin light-chain restriction. EBV-positive lymphocytes were scattered throughout the paracortical areas. Corticosteroid treatment was very effective. IgG4-related lymphadenopathy has a broad histological spectrum and might be misdiagnosed due to other conditions which morphologically closely resemble it. The correct diagnosis is important in view of the remarkable response to steroid therapy.

Nodal inflammatory pseudotumor caused by luetic infection

Inflammatory pseudotumor of lymph nodes (IPT-LN) represents an unusual cause of lymphadenitis of unknown etiology. Upon the observation of a case of IPT-LN associated with Treponema pallidum (Tp) infection, we analyzed a series of 9 IPT-LN and 9 extranodal IPT (spleen, 4 cases; lung, orbit, gut, skin, and liver) for the presence of Tp, using a polyclonal antibody anti-Tp. At the time of biopsy, none of the patients was suspected for luetic infection, nor specific serologic tests were available. IPT-LN areas extensively involved the nodal parenchyma in 4 cases, whereas they were focal in the remaining 5 cases. Capsular thickening and inflammation (6/9), venulitis (3/9), small granulomas (3/9), and follicular hyperplasia (7/9) were observed in the associated lymphoid parenchyma. Tp were detected in 4/9 cases of LN-IPT and in none of the extranodal IPT. Tp were extremely abundant within the IPT areas and in the perivascular tissues in the surrounding parenchyma, whereas they were scattered within the capsule. In Tp+ cases, marked follicular hyperplasia was the single distinctively associated feature. Double immunostains revealed that Tp were predominantly contained in the cytoplasm of CD11c+ CD163+ macrophages, some of which co-expressed HLA-DR. In addition, scattered S100+ interdigitating dendritic cells also showed intracytoplasmic Tp. This study shows that a significant number of IPT-LN is associated with Tp infection. A spirochetal etiology can be suspected in cases of IPT-LN, independently from the extension of the lesions, especially when pronounced follicular hyperplasia is found. Infection by Tp of macrophages and dendritic cells are in keeping with in vitro data and indicate that immune mediated mechanisms may be involved in the pathogenesis of the lesions.

Follicular lymphoma with prominent sclerosis (“sclerosing variant of follicular lymphoma”) exhibiting a mesenteric bulky mass resembling inflammatory pseudotumor. Report of three cases

We present three cases of follicular lymphoma (FL) exhibiting prominent sclerosis (sclerosing variant of follicular lymphoma), resembling inflammatory pseudotumor (IPT) of the lymph node, arising from mesenteric lymph node. Clinically all three cases represented bulky masses of the mesenteric lymph node. Histologically, the lesions were characterized by neoplastic lymphoid follicles separated by stromal collagenization and sclerotic process, with cellular infiltrate extending into the adjacent adipose tissue. The lesions contained variable cellular spindle cell proliferation and inflammatory infiltrate including numerous reactive T cells and histiocytes. Small capillary proliferation with vascular change was also noted. Immunohistochemical study demonstrated the myofibroblastic nature of the spindle cells. Moreover, neoplastic follicles were composed of intermediate to medium-sized lymphocytes, somewhat resembling reactive lymphoid aggregates. The overall histomorphological findings of the three lesions were similar to those of IPT of the lymph node. However, CD10, Bcl-2 and Bcl-6 immunostaining demonstrated the neoplastic nature of the lymphoid follicles and the lesions were diagnosed as FL grade 1. The present three cases indicate that the sclerosing variant of grade 1 FL should be added to the differential diagnosis from IPT of the lymph node.

Abdominal inflammatory masses mimicking neoplasia in children-experience of two centers

Despite progress in modern imaging, some inflammatory masses are difficult to distinguish clinically from neoplastic processes. In such cases the pathology report has a great distinctive value, but even then the final diagnosis may be difficult to reach. Eight patients with abdominal tumors of inflammatory origin were treated in two institutions, the Department of Pediatric Surgery of the Medical University of Gdansk, Poland, and Helios Center of Pediatric Surgery in Berlin, Germany, during the last 10 years. Four tumors were located in the pelvis, two in the liver, and two in the colonic mesentery. Five of them were inflammatory pseudotumors (two subclassified as inflammatory fibrosarcoma), one had nonspecific inflammatory changes, one was diagnosed as idiopathic retroperitoneal fibrosis, and one was diagnosed as bacillary angiomatosis. All patients underwent surgical tumor biopsy, excisional in four and incisional in four. All but two children underwent macroscopically complete tumor excision (four primarily, two secondarily). In one case the tumor resolved with antibiotherapy. Surgery in retroperitoneal masses was often extensive and associated with significant complications because of invasive tumor growth. In conclusion, intraabdominal inflammatory lesions may closely mimic neoplasia in children. Clinical doubts result in repeated biopsies, and for this reason excisional biopsy should be preferred. In some cases, when excisional biopsy is not feasible due to invasive growth of the tumor, delayed complete mass excision should follow, despite occasional significant morbidity. The etiology and exact nature of inflammatory pseudotumors are still obscure, and it is unknown whether they represent inflammatory lesions or true neoplasia.

[Inflammatory pseudotumor of lymph node]

INTRODUCTION

Inflammatory pseudotumor of lymph node is a rare case in the etiology of fever of unknown origin.

OBSERVATION

We report the observation of a woman, aged 40, hospitalized with intermittent fever revealing under-diaphragm adenopathy related to inflammatory pseudotumor of lymph node.

CONCLUSION

Inflammatory pseudotumor of lymph node is a rare pathology whose nosological definition is unclear. It should probably be considered as belonging to a category different from the inflammatory pseudotumor of other organs. The diagnosis presents itself in case of isolated adenopathy or prolonged fever and is based on an anatomopathology that essentially calls to mind a lymphoma. The evolution of the condition is shown to be favorable : it can lead to a spontaneous remission, or call for a non-steroid anti-inflammatory treatment, or a steroid therapy.