A rare case of IgG4-related disease: a gastric mass, associated with regional lymphadenopathy

Background IgG4-related disease (IgG4-RD) is a newly recognized disorder, characterized by massive IgG4+ lymphocyte and plasma cell infiltration, storiform fibrosis, causing enlargement, nodules or thickening of the various organs, simultaneously or metachronously. Involvement of the gastrointestinal tract is very rare and can be presented as a diffuse wall thickening or polyp or mass-like lesion. Up to now, there have been reported only a few cases of isolated gastric IgG4-RD. Case presentation We present an unusual case of IgG4-RD of the stomach with involvement of the regional lymph nodes, clinically manifested as a gastric cancer with related pyloric stenosis. The patient underwent distal gastrectomy, omentectomy and lymph node dissection. The postoperative serum IgG4 level was increased. The diagnosis was confirmed by immunohistochemical study. Conclusions In the most of the reported cases there was not sufficient data about the regional lymph nodal status, although the majority of the patients had been operated with presumptive diagnosis of gastric neoplasm. Our case is rare and valuable because it presents a gastric IgG4-related lesion larger than all previously reported in literature, and IgG4-related lymphadenopathy, confirmed histologically, which contributes to better knowledge of the disease.


Case presentation
We described the case of suspected gastric IgG4-RD and regional lymphadenopathy, misdiagnosed as a gastric cancer. A 62-year-old female presented with symptoms of severe weakness and fatigue. Laboratory tests revealed anemia (hemoglobin 58 g/L). Because of these the patient had been admitted to another hospital where a gastric tumor and related pyloric stenosis were found with gastroscopy and several blood transfusions were performed. The biopsy showed a chronic ulcerative lesion with suspected atypical cells in the bottom. Computer tomography (CT) revealed prepyloric irregular thickening of the gastric wall up to 15 mm which involved its entire circumference. The patient's co-morbidities included Henoch-Schonlein purpura, allergy to analgesics, arterial hypertension and depressive disorder. Several years ago, the patient had undergone cholecystectomy and plastic of hiatal hernia. The physical examination of the abdomen did not reveal any pathological findings. Given the presumptive diagnosis of gastric cancer, the patient was hospitalized in our department for surgical treatment. A distal gastrectomy, omentectomy and lymph node dissection were performed. The diagnosis was confirmed with histological and immunohistochemical study.
Grossly, there was an ulcer-infiltrative tumor formation, 8/3 cm in size, involving gastric lesser curvature, the front and posterior wall of the stomach. The tumor infiltrated the lesser omentum and penetration into the serosa was probable. The surrounding mucosa was scattered with petechial hemorrhages (Fig. 1).
Microscopic examination of the gastric formation showed tumor-like proliferation with mixed cellular composition: predominantly CD79a + mature B-cells, organized in follicular structures and located diffusely; abundance of mature CD 138+ plasma cells and significant presence of eosinophils ( Fig. 2 a, b and c). There was marked fibrosis in lamina propria, often in a storiform pattern of growth, induced by the lymphocyte and plasma cell infiltration. Proliferation of vessels, the same cellular infiltration and obliterative phlebitis were found, too. Sixteen lymph nodes were isolated. Histologically, they were characterized by preserved capsule thickness, presence of lymph follicles in the entire area of the node with activation changes, expressed in different degrees, and predominantly regressive changes of the germinal centers -depletion of the normal composition, vascularization, compact FDC-nets, dominated by CD 23+ cells (Fig. 2d). There were groups and bundles of mature CD 138+ plasma cells in the interfollicular areas (Fig. 2e). Immunohistochemical study was performed and abundance of positive IgG4 plasma cells was proved (Fig. 2f). In the gastric lesion there were more than 50 IgG4-positive lymphoplasmacytic cells per highpowerfield.

Discussion
IgG4-RD was firstly described in patients with sclerosing cholangitis, called autoimmune pancreatitis (AIP) type I, and later observed in other organs [1]. The comprehensive diagnostic criteria for IgG4-RD include: 1/diffuse or partial enlargement, swelling, nodules, or thickening lesion on single or multiple organs, 2/a serum IgG4 concentration more than 135 mg/dL, 3/histological changes a/massive lymphocytic and plasmacytic infiltration and sclerosis, b/increased number of IgG4+ plasma cells; and IgG4+/IgG+ plasma cell ratio >40 % and > 10 cells per high-powered field. Patients fulfilling all three criteria can be diagnosed definitively with IgG4-RD, those who fulfill criteria 1 and 3 have a probable diagnosis, and in those who fulfill criteria 1 and 2 the diagnosis is possible [1,5]. However, these criteria do not include gastric localization of the disease. So a recent study established that infiltration of IgG4+ plasma cells in the stomach mucosa only cannot be diagnosed as gastrointestinal lesion of IgG4-RD [4]. This diagnosis can be made if there is diffuse wall thickening or polyp or mass-like lesion with relevant histological changes [4]. According to this, we found several cases of gastric IgG4-RD, reported in literature [3,[6][7][8][9][10][11][12][13]. A summary of them is described in Table 1.
The most gastric IgG4-RD was detected in middle-aged patients (45 to 75 years) with predominance of women, although the total number of patients is too small to reveal any meaningful data. The body of the stomach was affected mainly. The size was variable (8-56 mm in cases reported in literature) and tumor in our case was considerably larger than the other gastric lesions of IgG4-RD. In most of the cases the gastric lesion was solitary. The two patients with multiple polyps in the stomach also had AIP and autoimmune endocrinopathy, respectively. In 7 of all reported cases, there were associated autoimmune diseases. In four of these patients there was multi-organ involvement of IgG4-RDone patient with concomitant AIP, one casewith AIP and IgG4-related sialadenitis, one patient with localization of the disease in stomach, lungs, skin and lymph nodes and our patient had lymphonodal involvement, too. The IgG4-related lymphadenopathy, as in our case, can be confirmed only by histological examination. According to criteria, classified by Sato et al. histological changes include: 1/ Castleman's disease-like morphology; 2/reactive follicular hyperplasia, 3/interfollicular plasmacytosis and immunoblastosis, 4/progressive transformation of germinal center-like, and 5/inflammatory pseudotumorlike morphology [1,14].
In most of the reported cases of gastric IgG4-RD there was not sufficient data about the lymph nodal status, although they were treated surgically with presumptive diagnosis of gastric neoplasm. In our case the accurate lymph nodal dissection was performed and IgG4-related lymphadenopathy was confirmed immunohistochemically. No enlarged lymph nodes had been detected on CT and the dissection was carried out only because we had suspected oncological disease. So if we had not done it, we would have missed the involvement of lymph nodes of IgG4-RD.
The first therapeutic choice for management of IgG4-RD is the steroid treatment [1,3]. However, most patients with gastric IgG4-RD were treated surgically, except one patient with concomitant AIP who underwent steroid therapy. This is probably because IgG4-RD frequently might be misinterpreted clinically and radiologically as a neoplasm [1][2][3][4]. In our case the surgery was necessary not only because of the suspected gastric cancer, but for the relevant pyloric stenosis.

Conclusions
Most gastric IgG4-RD lesions are difficult to diagnose because of their rarity and it is of utmost importance to exclude neoplasm. Unnecessary surgery can be avoided if the IgG4-RD of the stomach is considered in the differential diagnosis. Our case is rare and valuable because it presents a gastric IgG4-related lesion larger than all previously reported in literature, and IgG4-related lymphadenopathy, confirmed histologically, which contributes to the better knowledge of the disease.

Acknowledgement
The authors appreciate the patient's approval to present this case and acknowledge all the medical and surgical staff that took care of the patient.

Funding
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Availability of data and materials
The data sets supporting the conclusions of this article are included within the article.

Authors' contributions
Elena Arabadzhieva wrote the paper and collected the literature for the review in the report. Sasho Bonev analysed the review. Atanas Yonkov and Dimitar Bulanov performed the operation of the patient described in this report. Tihomir Dikov and Diana Kyoseva performed the histological examination and the immunohistochemical study and confirmed the diagnosis. Violeta Dimitrova revised the manuscript for important intellectual content and technical details. All authors have read and approved the final manuscript.

Competing interests
The authors declare that they have no competing interests.

Ethics
The patient's approval has been given for publication of this case report.