Somatic hypermutation of immunoglobulin heavy chain variable region genes in thymic marginal zone B-cell lymphoma of MALT type of a patient with Sjögren's syndrome

Lymphomas of the Mediastinum and Their Differential Diagnosis

Lymphoma is the most common malignancy involving the mediastinum but can be challenging to diagnose on small biopsy specimens. This review provides a pattern-based approach to help triage small tissue samples for the diagnosis of mediastinal lymphoid proliferations, with focus on the main primary mediastinal lymphomas. The use of ancillary studies is highlighted, along with considerations to avoid misdiagnosis and scenarios to request additional tissue.

Primary hepatic mucosa-associated lymphoid tissue lymphoma and hemangioma with chronic hepatitis B virus infection as an underlying condition

Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma has a low incidence and is a rare subtype of hepatic malignant lymphoma. Described here is a rare case of primary hepatic MALT lymphoma and hepatic hemangioma with chronic HBV infection as an underlying condition. Possible treatment modalities, which should be selected in accordance with tumor size, tumor location, tumor number, and underlying liver disease, are discussed in conjunction with a review of the literature. In addition, the potential use of hepatic resection, radio frequency ablation (RFA), or radiotherapy followed by chemotherapy via the R-CHOP regimen is also discussed.

Primary MALT-type lymphoma of the thymus: a clinicopathological and immunohistochemical study of six cases

BACKGROUND

Six cases of primary extranodal marginal zone B-cell lymphoma of the thymus (MALT [mucosa-associated lymphoid tissue]) are described.

METHODS

The patients were all women between 48 and 59 years. Clinically, all patients, except for one, were Caucasians. Two patients had a history of autoimmune disease, while one was being investigated for such a possibility. The remaining three patients did not have a history of autoimmune disorders.

RESULTS

In those patients who had symptoms related to their anterior mediastinal masses, nonspecific symptoms, including shortness of breath and chest pain, predominated. Histologically, the tumors had the classical morphologic features of cystic and solid areas with an atypical monocytoid cellular proliferation. Immunohistochemical stains performed in all cases showed kappa monotypic expression and B-cell phenotype.

CONCLUSIONS

The current cases highlight that MALT lymphomas of the thymus can occur in a setting not related to autoimmune disease or in those not of Oriental ethnic background and that mediastinal cystic lesions require proper sampling in order to adequately evaluate the possibility of MALT lymphoma.

[Association between thymic MALT lymphoma and Sjögren's syndrome]

INTRODUCTION

Thymic mucosa-associated lymphoid tissue (MALT) lymphoma is a rare pathology, often associated with autoimmune diseases. The authors report the case of an Asian woman with Sjögren's syndrome.

OBSERVATION

A 48-year-old Chinese woman, without past medical history and a non-smoker, presented an alteration in her overall condition, dyspnoea at exercise, inflammatory polyarthralgia, and a dry eye and mouth syndrome over the last few months. Thoracic tomodensitometry detected an anterior heterogenic cystic mediastinal mass. A mediastinotomy was performed. The diagnosis of the surgical biopsy was thymic MALT lymphoma. The authors also diagnosed Sjögren's syndrome with the presence of four diagnostic criteria. Chemotherapy by rituximab, cyclophosphamide, vincristine, prednisone induced major tumoral regression. The patient declined surgery and will be monitored.

CONCLUSION

Thymic MALT lymphoma is a rare pathology. There is a high correlation with autoimmune diseases, like Sjögren's syndrome. Its appearance is that of an anterior mediastinal mass with a cystic component. The treatment is not well codified and is most often based on surgical resection, eventually followed by chemotherapy or radiotherapy. As far as the authors know, this is the second case of thymic MALT lymphoma treated by exclusive chemotherapy.

Mucosa associated lymphoid tissue (MALT) lymphoma of the thymus with trisomy 18

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) of the thymus is rare and little is known about its karyotype abnormality. MALT lymphoma in general shows a good prognosis, but some reports suggest that the presence of trisomy 18 predicts recurrence. Here, we report a patient with MALT lymphoma of the thymus and the left parotid gland accompanied by Sjogren's syndrome. The karyotype analysis revealed that this is the first case of thymic MALT lymphoma with trisomy 18, which we believe is worth reporting. We also review cases with thymic MALT lymphoma previously reported in the literature.

Thymic and pulmonary mucosa-associated lymphoid tissue lymphomas in a patient with Sjögren’s syndrome and literature review

Mucosa-associated lymphoid tissue lymphoma (MALToma) has been reported in several organs. Among MALTomas, thymic and pulmonary MALTomas are rare. The present report describes a patient with Sjögren's syndrome who presented thymic and pulmonary MALTomas. Although the exact pathogenetic relationship between these two tumours is uncertain, it is likely that the underlying immune dysregulation related to Sjögren's syndrome contributed to the occurrence and the unusual manifestation of MALTomas in this patient.

ImmunoglobulinVH genes in thymic MALT lymphoma are biased toward a restricted repertoire and are frequently unmutated

Thymic MALT lymphoma shows certain distinctive features among MALT lymphomas, such as expression of IgA isotype, consistent lack of API2-MALT1 gene fusion, and very strong association with autoimmune disease, especially Sjogren's syndrome. To help clarify the nature of the clonal lymphoid infiltrates, we analysed the usage and somatic hypermutation of the Ig heavy chain variable region (V(H)) genes in nine different cases. The V(H) rearrangement was potentially functional in all cases and was restricted to the V(H)3 family. V(H) usage was biased toward V(H)3-30 (five cases) and V(H)3-23 (three cases) segments, which have both been frequently expressed by autoimmune B cells. Somatic hypermutation was absent in five cases. Fewer than the expected replacement mutations were found in the framework regions in two cases, indicating a negative antigen selection pressure. Ongoing mutation was absent in all cases. D segment usage was varied, whereas J(H) segment usage was restricted to J(H)4. The observed patterns of V(H) usage and mutations suggested that specific antigens may play a pathologically relevant role in the genesis or progression of thymic MALT lymphoma.

Mucosa-associated lymphoid tissue lymphoma of the thymus: a case report with no evidence of MALT1 rearrangement

We report a case of thymic mucosa-associated lymphoid tissue (MALT) lymphoma (TML) that presented as an asymptomatic mediastinal mass in a 40-year-old woman with a past history of Sjögren syndrome. This case had the characteristic clinical and pathological features of TML, as found in most of the 24 previously reported cases, i.e., autoimmune context, especially Sjögren syndrome, IgA secretion, large epithelial cysts, lymphoepithelial lesions involving residual Hassal's corpuscles, epithelial cysts, and a marked plasmacytic differentiation with IgA expression. Reverse-transcription polymerase chain reaction for t(11;18)(q21;q21) was negative, in agreement with recently published data. In this case, investigation for t(14;18)(q32;q21) using fluorescent in situ hybridization was also performed and supplied negative results. Neoplastic cells were negative for MAL, a marker of primary mediastinal large B cell lymphoma (PMBL). Altogether, these findings further support that among MALT lymphomas, TML have peculiar clinical and morphological characteristics and appear not to involve MALT1 rearrangement. They also suggest the absence of a relationship between TML and PMBL.

Hepatic mucosa-associated lymphoid tissue lymphoma and hepatocellular carcinoma in a patient with hepatitis B virus infection

Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma is an extremely rare disease. A 65-year-old female patient with chronic hepatitis B presented with multiple solid masses in segment (S) 4, S5, and S6 of the liver. The nodule in S5 was diagnosed preoperatively as hepatocellular carcinoma by computed tomography, magnetic resonance imaging, and angiography. The nodule in S4 was initially interpreted as lymphoid follicles by needle biopsy. Segmentectomy of S5 and partial resection of S6 were performed. Microscopic examination of the S5 nodule revealed moderately differentiated hepatocellular carcinoma. The nodule from S6 showed nodular proliferation of atypical intermediate to medium-sized lymphoid cells in the portal area and lymph epithelial lesions of bile ducts. The atypical lymphoid cells were positive for LCA, L-26 and bcl-2 and negative for UCHL-1. These features were consistent with the diagnosis of MALT lymphoma. This is the first case report of synchronous hepatic MALT lymphoma and hepatocellular carcinoma associated with chronic hepatitis B.

New concepts in the pathogenesis of Sjögren syndrome: many questions, fewer answers

Although a modified European-American consensus classification of Sjögren syndrome has been introduced during the last year, the etiopathogenesis of this disease characterized by chronic lymphocytic inflammation, impaired function, and, finally, destruction of the salivary and lacrimal glands as well as systemic manifestations remains to be elucidated. Recent insights into the pathogenesis of Sjögren syndrome resulting from immunogenetic, hormonal, and epidemiologic evaluations as well as animal and in vitro studies are highlighted by this review. Evidence confirms that lymphocytic disturbances, including ectopic germinal center formation and aberrations of cellular signaling play a significant role in Sjögren syndrome. Although some of these features are unique to Sjögren syndrome, others are also found in a number of systemic autoimmune diseases, such as systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. The underlying cause of Sjögren syndrome remains largely enigmatic. However, distinct characteristics may provide the basis for the classification of the disease entities. Finally, an enhanced risk of lymphomagenesis is a well-known hallmark of primary Sjögren syndrome, indicating the central role of derangement of lymphocyte regulation. As demonstrated by the introduction of the new targeted therapeutic approaches in rheumatoid arthritis, solid insights into the pathogenesis of Sjögren syndrome may pave the way toward new therapeutic approaches.

Primary thymic extranodal marginal-zone B-cell lymphoma of mucosa-associated lymphoid tissue type exhibits distinctive clinicopathological and molecular features

Extranodal marginal-zone B-cell lymphoma (MZBL) of mucosa-associated lymphoid tissue (MALT) arising in the thymus is rare, with the largest series in the literature including only three cases. In the present study, we investigated 15 cases of thymic MALT lymphoma to systematically characterize its clinical, histopathological, and molecular features. There was a marked female predilection (male:female = 1:4), with a mean age of 55 years at diagnosis. There was a strong association with autoimmune disease, especially Sjögren's syndrome. Histologically, the thymic lymphoma showed the characteristic morphological features of extranodal MZBL of MALT type. Cysts were common. Prominent lymphoepithelial lesions were formed by centrocyte-like cells infiltrating and expanding the Hassall's corpuscles and epithelium lining the cysts. Plasmacytic differentiation was apparent in all cases. Notably, 13 of 15 cases expressed immunoglobulin (Ig) A phenotype; IgA expression in thymic MALT lymphoma was in striking contrast with the IgM phenotype observed in most of the Sjögren's syndrome-associated MZBLs and MALT lymphomas at other sites. Epstein-Barr virus was absent, and API2-MALT1 gene fusion, a recently reported MALT lymphoma-specific gene abnormality, was not detected in any case. Although one patient died of disease 85 months after the diagnosis, other patients were alive with overall 3-year and 5-year survival rates being 89% and 83%, respectively. Among the 22 patients reported previously and in the present series, at least 17 patients (77%) were Asians. These data indicate that thymic MALT lymphoma may represent a distinct subgroup of MALT lymphoma characterized by apparent predilection for Asians, a strong association with autoimmune disease, frequent presence of cysts, consistent plasma cell differentiation, tumor cells expressing IgA phenotype, and consistent lack of API2-MALT1 gene fusion.