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

The MAL Family of Proteins: Normal Function, Expression in Cancer, and Potential Use as Cancer Biomarkers

The MAL family of integral membrane proteins consists of MAL, MAL2, MALL, PLLP, CMTM8, MYADM, and MYADML2. The best characterized members are elements of the machinery that controls specialized pathways of membrane traffic and cell signaling. This review aims to help answer the following questions about the MAL-family genes: (i) is their expression regulated in cancer and, if so, how? (ii) What role do they play in cancer? (iii) Might they have biomedical applications? Analysis of large-scale gene expression datasets indicated altered levels of MAL-family transcripts in specific cancer types. A comprehensive literature search provides evidence of MAL-family gene dysregulation and protein function repurposing in cancer. For MAL, and probably for other genes of the family, dysregulation is primarily a consequence of gene methylation, although copy number alterations also contribute to varying degrees. The scrutiny of the two sources of information, datasets and published studies, reveals potential prognostic applications of MAL-family members as cancer biomarkers-for instance, MAL2 in breast cancer, MAL2 and MALL in pancreatic cancer, and MAL and MYADM in lung cancer-and other biomedical uses. The availability of validated antibodies to some MAL-family proteins sanctions their use as cancer biomarkers in routine clinical practice.

Mucosa-associated lymphoid tissue lymphoma in thymus: a SEER analysis

OBJECTIVES

The present study explores an extremely rare disease, thymic mucosa-associated lymphoid tissue (MALT) lymphoma, for its characteristics and prognostic factors by analyzing the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

From 2000 to 2018, cases with a diagnosed thymic MALT lymphoma were extracted. Clinical characteristics, treatments, and survival patterns of these cases were analyzed.

RESULTS

Thymic MALT lymphoma (n = 26) accounted for 0.09% of all MALT lymphomas. With a sex ratio of 0.53 (male/female), 68% white population was affected. Most cases were diagnosed with Ann Arbor stage I (50%), yet advanced-stage did not show worse prognosis (p = 0.236). Different treatment protocols did not influence the overall prognosis (p > 0.99). The 5- and 10- year overall survival rates were 83.1% and 78.2%, respectively. Older than 70 years may be an independent risk factor for overall survival (HR = 7.166 [95% CI 1.173-43.756], p = 0.033).

CONCLUSION

Thymic MALT lymphoma is a highly rare disease with a favorable prognosis. Ann Arbor staging might not be appropriate to classify severity of this disease or its treatment. Older people may have worse survival. A standardized treatment mode needs to be established, and surgery could remain as the mainstay.

Mediastinal Lymphoproliferative Disorders

Lymphoproliferative disorders comprise 50% to 60% of all mediastinal malignancies in both children and adults. Primary mediastinal involvement is rare (∼5%), whereas secondary mediastinal involvement by systemic disease is more common (10% to 25%). Primary mediastinal disease is defined as involvement by a lymphoproliferative disorder of mediastinal lymph nodes, the thymus, and/or extranodal mediastinal organs without evidence of systemic disease at presentation. In this review, the clinical, radiologic, histopathologic, immunohistochemical, and genetic features of some of the most characteristic mediastinal lymphoproliferative disorders are presented. The entities discussed here include: classic Hodgkin lymphoma with emphasis on nodular sclerosis and mixed cellularity types, and non-Hodgkin lymphomas, including primary mediastinal (thymic) large B-cell lymphoma, mediastinal gray zone lymphoma, mediastinal diffuse large B-cell lymphoma, thymic marginal zone lymphoma, mediastinal plasmacytoma, T-lymphoblastic lymphoma, and anaplastic large cell lymphoma. Although not a malignant process, hyaline vascular Castleman disease is also discussed here as this disorder commonly involves the mediastinum. Despite multiple advances in hematopathology in recent decades, the day-to-day diagnosis of these lesions still requires a morphologic approach and a proper selection of immunohistochemical markers. For this reason, it is crucial for general pathologists to be familiar with these entities and their particular clinicoradiologic presentation.

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 thymic mucosa-associated lymphoid tissue lymphoma: 7 clinical cases report and a review of the literature]

Objective: To reveal clinical features, pathological diagnosis, treatment and prognosis of primary thymic mucosa-associated lymphoid tissue (MALT) lymphoma and review literatures. Methods: The clinical characteristics, pathological diagnosis, laboratory texts, treatment and prognosis of 7 cases of primary thymic MALT lymphoma identified at the First Affiliated Hospital of Nanjing Medical University from November 2017 to January 2019 were collected and analyzed. Results: Of 7 primary thymic MALT lymphoma cases, six were female. Patients were often asymptomatic and were found mediastinal mass by chest CT. After mediastinal mass resection, pathologist reported a primary thymic MALT lymphoma. Laboratory tests showed all patients were positive for anti-nuclear antibody, anti-Ro52 antibodies and anti-Sjogren's syndrome A antibodies, and increased erythrocyte sedimentation rate (ESR) . Four were diagnosed with Sjogren's syndrome (SS) . After surgery, the patients were given the positron emission tomography computed tomography (PET-CT) scans. All cases received "watch and wait" approach. Up to now, all cases showed good prognoses and none of them relapsed. Conclusion: Primary thymic MALT lymphoma was rare, and it was often associated with autoimmune diseases. Such patients who usually had good prognoses should be followed up closely and avoided excessive treatments if there were no indications of intervention.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 2

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ∼5% of all non-Hodgkin lymphomas (NHLs) and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal (PM) large B-cell lymphoma and T-lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both Epstein-Barr virus positive), and pleural and/or pericardial primary effusion lymphoma (human herpesvirus-8 positive/Epstein-Barr virus positive). We review the historical aspects, epidemiology, clinicoradiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of the remaining mediastinal B-cell lymphomas, including primary thymic marginal zone lymphoma of the mucosa-associated lymphoid tissue type, other PM small B-cell lymphomas, PM plasmacytoma, and the most relevant PM T-cell lymphomas.

Thymic Extranodal Marginal Zone Lymphoma of Mucosa-associated Lymphoid Tissue with 8q24 Abnormality

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) of the thymus is reported to have characteristic features that distinguish it from MALT lymphoma of other organs; it is proposed to be a distinct clinicopathological subgroup of MALT lymphoma. We herein present a case of thymic MALT lymphoma accompanied by Sjögren's syndrome, involving the first report of a thymic MALT lymphoma patient carrying a chromosomal abnormality of 8q24. No c-myc gene translocation or c-Myc protein overexpression was observed, suggesting that c-myc was not involved in lymphomagenesis or progression. Although we did not examine the mechanisms by which the lymphoma developed, this chromosomal structural change in 8q24 may be associated with the pathogenesis in our case.

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.

Thymic extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue: a clinicopathological and genetic analysis of six cases

We investigated six new cases of primary thymic extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) to further characterize the clinicopathological and genetic features. The male to female ratio was 1:1. One female patient had suffered from systemic lupus erythematosus. Another female patient was diagnosed with rheumatoid arthritis after thymectomy. One patient had a concurrent tumor in the eyelid. Radiologically, all tumors were located in the prevascular space and presented as asymmetric heterogeneously enhanced cystic and solid masses. MALT1, BCL10 or IGH translocations and trisomy 18 were not observed in any cases by fluorescence in situ hybridization (FISH) analysis. Trisomy 3 was detected in one patient and another showed a TNFAIP3/A20 deletion. Meta-analysis (n = 51) including the present and previously reported cases revealed that the prevalence of autoimmunity was much lower in males with thymic MALT lymphoma compared to females (33% vs. 87%, p = 0.001). Additionally, the average age of females or patients with autoimmunity was about 10 years younger than that of males or patients without autoimmunity (p = 0.003 and p = 0.008, respectively). In summary, thymic MALT lymphoma arising without underlying autoimmunity frequently involves males or older patients. Trisomy 3 and an A20 deletion might play a role in the pathogenesis of thymic MALT lymphoma.

Two malignant tumours in the anterior mediastinum positive for CD5

To our knowledge, the simultaneous involvement of the anterior mediastinum by a thymic carcinoma and a B-cell chronic lymphocytic leukaemia has not been reported previously. The authors describe the case of a 62-year-old man, suffering from severe bronchitis. Chest x-ray and CT scan showed a mediastinal tumour, resected short-time after diagnosis. First, standard based histological examination revealed a thymic carcinoma admixed by a dense lymphatic infiltrate. Additional immunohistochemical staining for CD5-labelled epithelial thymic carcinoma cells as well as neoplastic B cells and led in combination with blood tests to confirm the diagnosis of the composite occurrence of a thymic carcinoma and a B-cell chronic lymphocytic leukaemia.

Thymic mucosa-associated lymphoid tissue lymphoma associated with bilateral orbital pseudotumor

Mucosa-associated lymphoid tissue (MALT) lymphoma of the thymus is a rare condition, often characterized by its occurrence in a context of autoimmunity. We reported a first case of thymic MALT lymphoma following bilateral orbital pseudotumor. A 48-year-old man presented with bilateral exophthalmos diagnosed as orbital pseudotumor. His symptoms were relieved by an oral corticosteroid. Eleven years later, a mediastinal tumor was incidentally discovered. A thymectomy was performed, and histological examination revealed that the mass was a MALT lymphoma. There was no recurrence with no further treatment.

[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.

Mucosa-associated lymphoid tissue lymphoma of the thymus associated with Sjögren's syndrome: report of a case

A 68-year-old Japanese man with Sjögren's syndrome was pointed out to have a nodular shadow in the anterior mediastinum. The tumor was resected under video-assisted thoracoscopy and it was pathologically diagnosed to be thymic mucosa-associated lymphoid tissue (MALT) lymphoma. There has been no recurrence for 17 months after surgery. Mucosa-associated lymphoid tissue lymphoma of the thymus is rare, and its pathological diagnosis requires sufficient knowledge and experience. Since thymic MALT lymphoma is distinct from MALT lymphoma of other sites in several ways, including gene abnormalities and geographic distribution, an alternative oncogenic pathway and the influence of racial and/or environmental factors must be considered to be involved. However, since the number of reported thymic MALT lymphomas is limited, these issues are still unclear. The accumulation of further similar cases will help to elucidate various issues concerning thymic MALT lymphoma associated with Sjögren's syndrome.

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.