Mucosa-associated lymphoid tissue lymphoma of the thyroid with abundant IgG4-positive plasma cells

The Distinctive Nature of Thyroid MALT Lymphomas Including IRTA1 Expression

Mucosa-associated lymphoid tissue (MALT) lymphomas often express IgM and IRTA1 with only a minority demonstrating plasmacytic differentiation. However, like primary cutaneous marginal zone lymphoproliferative disorders (PCMZLPD), thyroid MALT lymphomas (T-MALT-L) frequently show plasmacytic differentiation and IgG positivity. Whether T-MALT-L share other features with PCMZLPD, including frequent IgG4 positivity and infrequent IRTA1 expression, and how IRTA1 staining compares to that in Hashimoto thyroiditis (HT) are unknown. Therefore, the clinicopathologic features of 18 T-MALT-L were assessed, and their IRTA1 expression compared with that in 5 HT cases. All T-MALT-L cases included a B-lymphoid component. Plasmacytic differentiation was present in 15 cases and was extensive in 12. Fourteen cases were IgG+ including 2 IgG4+ (12 κ+, 2 κ-/λ-). One case was IgAλ+. Plasmacytic cells were uniformly CD19+/CD56- but CD138- in 7/15 cases. IRTA1+ cells were present in 16/16 cases, ranging from scattered cells to >50%. They were often concentrated in "MALT ball"-type lymphoepithelial lesions, perifollicular regions, and sometimes in germinal centers. IRTA1 positivity was also present in all HT cases, although it was never very extensive and often had a perifollicular distribution, occasionally with sparse aggregates and positive cells within rare thyroid follicles. Thus, T-MALT-L share some features with PCMZLPD but are more similar to noncutaneous MALT lymphomas, with prominent lymphoepithelial lesions, ubiquitous although variable IRTA1 positivity, and infrequent IgG4 positivity. Plasmacytic differentiation is also common although CD138 loss is frequent and light chain staining may be absent. IRTA1 staining may help in the differential diagnosis with HT, although there is some overlap in staining patterns.

Clinical differences between IgG4 Hashimoto's thyroiditis and primary thyroid lymphoma

Background

Hashimoto's thyroiditis (HT) can be divided into IgG4 HT and non-IgG4 HT based on IgG4 and IgG immunohistochemical staining. In clinical practice, it is often necessary to identify diseases such as primary thyroid lymphoma (PTL) and IgG4 HT when a patient presents with a rapidly enlarged thyroid. The aim of our study was to uncover the differential points between the two diseases.

Methods

Clinical information from 19 IgG4 HT and 10 PTL patients was obtained from the patients' medical records, including age, sex, main clinical manifestation, thyroid functional status, the presence of serum anti-thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and thyroid ultrasonography results. Thyroid sections from all patients were collected to detect IgG4 and IgG expression by immunohistochemical staining.

Results

The IgG4 HT patients were significantly younger than those in the PTL group (39.68 ± 10.95 vs 66.20 ± 10.23 years, P < 0.001). There were no significant differences in the sex distribution or TgAb- or TPOAb-positive rates. The PTL group had a higher prevalence of clinical hypothyroidism than the IgG4 HT group (P = 0.016). In the PTL group, thyroid lesions were more likely to exhibit hypoechogenicity (6/6 vs 1/19, P < 0.001) on ultrasound images. In the PTL group, two patients met the immunohistochemical cut-off value of the criteria for IgG4 HT.

Conclusions

Simply relying on immunohistochemistry for IgG4 cannot diagnose IgG4 HT correctly when a patient presents with rapid thyroid enlargement. A combination of clinical and pathological analyses will help distinguish IgG4 HT from PTL which may be with abundant IgG4-positive plasma cells.

Imaging of head and neck mucosa-associated lymphoid tissue lymphoma (MALToma)

Marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALToma) arises in extranodal sites in the head and neck. Chronic inflammatory, infectious or autoimmune conditions are implicated in its pathogenesis. Within the head and neck, MALToma is often multifocal and indolent and the imaging appearances may be mistaken for non-malignant disease in the head and neck. The aim of this article is to illustrate the varied radiological and clinical features of MALToma in the head and neck, an awareness of which is needed for timely and correct diagnosis to guide subsequent disease management.

Validation of the diagnostic criteria for IgG4-related kidney disease (IgG4-RKD) 2011, and proposal of a new 2020 version

Background

In 2011, the IgG4-related kidney disease (IgG4-RKD) working group of the Japanese Society of Nephrology proposed diagnostic criteria for IgG4-RKD. The aim of the present study was to validate those criteria and develop a revised version.

Methods

Between April 2012 and May 2019, we retrospectively collected Japanese patients with kidney disease, for whom data on serum IgG4 values and/or immunohistological staining for IgG4 in renal biopsy samples were available. These patients were classified as IgG4-RKD or non-IgG4-RKD based on the diagnostic criteria for IgG4-RKD 2011, and the results were evaluated by expert opinion. Accordingly, we developed some revised versions of the criteria, and the version showing the best performance in the present cohort was proposed as the IgG4-RKD criteria for 2020.

Results

Of 105 included patients, the expert panel diagnosed 55 as having true IgG4-RKD and 50 as mimickers. The diagnostic criteria for IgG4-RKD 2011 had a sensitivity of 72.7% and a specificity of 90.0% in this cohort. Of the 15 patients with true IgG4-RKD who were classified as non-IgG4-RKD, all lacked biopsy-proven extra-renal lesions, although many had clinical findings highly suggestive of IgG4-RD. The revised version to which “bilateral lacrimal, submandibular or parotid swelling, imaging findings compatible with type 1 autoimmune pancreatitis or retroperitoneal fibrosis” was added as an item pertaining to extra-renal organ(s) improved the sensitivity to 90.9% while the specificity remained at 90.0%.

Conclusion

The revised version has considerably improved test performance after addition of the new extra-renal organ item (imaging and clinical findings).

Marginal zone B-cell lymphoma: lessons from Western and Eastern diagnostic approaches

Marginal zone B-cell lymphomas (MZLs) are a group of clinically indolent B-cell lymphomas postulated to derive from memory B lymphocytes in the 'marginal zone' of secondary lymphoid tissue. Today, MZL is recognised as a nosological umbrella term encompassing distinct entities with some shared phenotypic and genotypic features, including extranodal marginal zone B-cell lymphoma (EMZL) or mucosa-associated lymphoid tissue (MALT) lymphoma, splenic MZL, and nodal MZL, accounting for approximately 70%, 20%, and 10% of MZLs, respectively. These lymphomas share some phenotypic and genotypic features and have some variants and related provisional diseases, but are different in regards to their clinical and molecular characteristics. In addition, they are frequently associated with chronic antigenic stimulation represented either by infectious agents, particularly bacteria and viruses, or autoimmune diseases as exemplified by Sjögren syndrome, Hashimoto thyroiditis, and newly recognised IgG4-related disease. Furthermore, several chromosomal translocations have been identified in EMZL. In this review, we will focus on the updated histopathological criteria and the main problems with differential diagnoses in order to aid the diagnostic approach in our routine practice.

Polymyositis with elevated serum IgG4 levels and abundant IgG4+ plasma cell infiltration: A case report and literature review

INTRODUCTION

Polymyositis (PM) is a type of autoimmune, inflammatory myopathy. IgG4-related disease (IgG4-RD) is a recently recognized disease entity characterized by elevated serum IgG4 levels and IgG4 plasma-cell infiltration of various organs. However, several reports have described cases of other diseases that present with those features, suggesting the importance of careful differential diagnosis. Herein, we report the first case of PM with elevated serum IgG4 levels and IgG4 plasma cells in the muscles, mimicking IgG4-RD.A 73-year-old woman visited our hospital because of proximal muscle weakness of both thighs. Her blood test showed high levels of serum creatinine kinase, aldolase, and IgG4. Magnetic resonance imaging of the thighs showed muscle edema. Needle electromyography showed findings typical of myositis. Histological analysis of her left quadriceps revealed infiltration of IgG4 plasma cells as well as CD8 T cells. Scattered necrotic and regenerating muscle fibers with no specific findings for IgG4-RD (storiform fibrosis and obliterative phlebitis) were typical for PM. We diagnosed her condition as PM and treated her with 40 mg/day of prednisolone that decreased levels of muscle enzymes and improved muscle weakness.

CONCLUSION

Our case indicated that PM could present with high serum IgG4 levels and IgG4 plasma-cell infiltration, mimicking IgG4-RD. Although the mechanism of IgG4 elevation in such PM is unclear, our case highlights the necessity to recognize that high serum IgG4 levels and IgG4 plasma-cell infiltration in organs are not specific for IgG4-RD.

Serum IgG2 and tissue IgG2 plasma cell elevation in orbital IgG4-related disease (IgG4-RD): Potential use in IgG4-RD assessment

AIMS

To determine the role of serum and tissue IgG2 in orbital biopsies with the histological features of IgG4-related disease (IgG4-RD) in comparison with non-IgG4-related orbital inflammatory disorders (OID), including autoimmune disorders.

METHODS

This is an international (Sheffield, UK, and Singapore) collaborative, retrospective case review of 69 patients (38 from Singapore National Eye Centre and 31 from Royal Hallamshire Hospital, Sheffield) with orbital inflammatory biopsies between 2002 and 2016. Clinical information and histology were reviewed and cases were classified into three groups: Group 1: IgG4-RD orbital inflammation (n=43); Group 2: idiopathic OID (n=12) and Group 3: autoimmune OID (n=14). Serum IgG1, IgG2, IgG3 and IgG4 levels were collated where available and immunohistochemistry (IHC) for tissue IgG2 plasma cells was performed.

RESULTS

Dual IHC showed IgG2 plasma cells as a distinct population from IgG4 plasma cells. Significant (twofold) serum IgG2 elevation was noted among IgG4-RD (group 1), idiopathic (group 2) and autoimmune OID (group 3). Similarly, significant elevation of tissue IgG2 plasma cells was also seen among IgG4-RD (group 1), idiopathic and autoimmune OID (groups 2 and 3).

CONCLUSIONS

Significant elevations of serum IgG2 and tissue IgG2 plasma cells are present in orbital IgG4-RD in comparison with non-IgG4 orbital inflammation (idiopathic and autoimmune OID), suggesting that IgG2 may play a role in IgG4-RD. A serum IgG2 cut-off >5.3 g/L was found to be 80% sensitive and 91.7% specific for orbital IgG4-RD, with an accuracy of 0.90. Tissue IgG2 and IgG4 subclass reporting may provide additional insight regarding the 'IgG4-RD' pathogenesis.

Sporadic occurrence of non-diagnosed IgG4-related disease in lymphoma patients with a previous Sjögren's syndrome diagnosis

BACKGROUND

IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder, which may affect many organs, and often comes to clinical attention due to tumor-like organ swelling or is identified incidentally by specific biopsy findings. Typical histopathology of IgG4-RD is lymphoplasmacytic infiltration rich in IgG4 + plasma cells (PCs), storiform fibrosis, and obliterative phlebitis. Patients with sicca symptoms can be misdiagnosed as primary Sjögren's syndrome (pSS) instead of IgG4-RD because of clinical and histopathological similarities. Moreover, an association with lymphoma development is described in both diseases. This study investigated signs of IgG4-RD in a population-based cohort of patients diagnosed with pSS complicated by lymphoma.

METHODS

Patients with pSS and lymphoma diagnoses and available lymphoma specimens were identified by linkage with the Swedish Patient Register 1964-2007 and the Cancer Register 1990-2007 (n = 79). Clinical data and lymphomas were reviewed and the diagnoses evaluated. All lymphoma tissues and available minor salivary gland biopsies (n = 11) were immunostained for IgG4 + PCs and evaluated for other histopathological signs of IgG4-RD. In a case with specific findings of IgG4-RD, other available tissue specimens of the same patient were investigated for IgG4-RD.

RESULTS

Only one patient of 79 (1.3%) had >10 IgG4 + PCs/high power field (HPF) in the lymphoma tissue, an unspecified low-grade B-cell lymphoma localized in the submandibular gland. This patient also had other histopathological features of IgG4-RD in the lymphoma and a surgical lung biopsy taken five years before lymphoma diagnosis and, therefore, fulfilled the criteria for IgG4-RD. Occasional IgG4 + PCs (<10/HPF) without signs of IgG4-RD were observed in another six lymphomas. No IgG4 + PCs were identified in the minor salivary gland biopsies.

CONCLUSION

Histopathological findings of IgG4-RD may co-exist with low malignant B-cell lymphoma in patients with initially suspected pSS and may be associated with an underlying IgG4-RD.

Role of IgG4 serology in identifying common orbital lymphoproliferative disorders

AIM

To explore the role of IgG4 serology in identifying common orbital lymphoproliferative disorders.

METHODS

Eighty-one patients with orbital lymphoproliferative diseases were treated in the Department of Ocular Oncology, Beijing Tongren Hospital, Capital Medical University between September 2010 and December 2012. Serum IgG4 levels were measured in 46 cases of idiopathic orbital inflammatory pseudotumor (IOIP), 17 benign lymphoepithelial lesion (BLEL), 12 cases of orbital mucosa-associated lymphoid tissue (MALT), and 6 cases of diffuse large B-cell lymphoma (DLBL) using immuno-scatter turbidmetry (ISTM).

RESULTS

The frequency of elevated IgG4 levels in patients with IOIP, BLEL, MALT, and DLBL was 30.43% (14/46), 76.47% (13/17), 8.33% (1/12), and 0.00 (0/6), respectively. Among the patients with elevated serum IgG4 levels, all IgG-IOIP patients were male, and 92.31% of the IgG4-BLEL patients were female (12/13). The mean serum IgG4 level of IgG4-IOIP patients was lower than that of individuals with IgG4-BLEL, but the variation in serum IgG4 levels was larger in IgG4-IOIP than IgG4-BLEL patients. Only one case of IgG4-MALT with elevated serum IgG4 levels had a medical history >10y, which was significantly longer than the MALT patients with normal serum IgG4 levels. There was no significant elevation of serum IgG4 levels in patients with DLBL.

CONCLUSION

Detecting serum IgG4 levels plays an important role in the differential diagnosis of orbital lymphoproliferative diseases.

Diffuse large B-cell lymphoma of the lacrimal sac arising from a patient with IgG4-related disease

A rare case of diffuse large B-cell lymphoma (DLBCL) possibly induced by IgG4-related disease is described. A 78-year-old woman was presented with a mass of the right lacrimal sac that extended to the inferior nasal meatus through the nasolacrimal duct. Pathological diagnosis was DLBCL with diffuse distribution of IgG4 + cells in the background of this lesion. The chronic inflammatory state of IgG4-related disease could have caused the development of DLBCL.

IgG4-positive extranodal marginal zone lymphoma arising in Hashimoto's thyroiditis: clinicopathological and cytogenetic features of a hitherto undescribed condition

AIMS

Hashimoto's thyroiditis was recently divided into IgG4-plasma cell-rich and IgG4-plasma cell-poor subtypes. The former, also known as IgG4 thyroiditis, is associated with clinical, serological, sonographic and morphological features that are distinctive from those of the non-IgG4 subgroup. We describe an interesting case of IgG4-positive mucosa-associated lymphoid tissue (MALT) lymphoma arising in a background of IgG4 thyroiditis.

METHODS AND RESULTS

The thyroid gland showed typical features of IgG4 thyroiditis, including characteristic patterns of fibrosis. A dense lymphoplasmacytic infiltrate diffusely involved the entire gland without formation of a destructive tumour mass. Lymphoepithelial lesions were prominent. There were abundant IgG4-positive plasma cells, with the IgG4/IgG ratio exceeding 40%. The IgG4-positive plasma cells were monotypic for kappa light chain, and there was monoclonal IGH rearrangement. Fluorescence in-situ hybridization revealed IGH translocation without translocation of MALT1, bcl-10, or FOXP1.

CONCLUSIONS

This represents the first case of IgG4-producing MALT lymphoma associated with IgG4 thyroiditis. IGH translocation with an unknown partner gene was identified. We suggest the performance of serum and immunohistochemical investigations for IgG and IgG4 in all cases of Hashimoto's thyroiditis to diagnose IgG4 thyroiditis. In addition, clonality assays and light chain studies are useful to exclude a low-grade lymphoma arising in this context.