A spectrum of Thymic mucosa-associated lymphoid tissue lymphoma and Thymic amyloidosis in the patient with Auto immune disease: a case series

Abstract

Background The thymus is associated with an immunodeficient status, autoimmune disease (AD), and the common thymic tumor, thymoma. We encountered two rare thymic tumors, thymic mucosa-associated lymphoid tissue (MALT) lymphoma and localized thymic amyloidosis, both in the presence of Sjögren’s syndrome (SjS). This suggests a possible link between rare thymic tumors and SjS. Therefore, we reviewed cases of thymic tumors to examine the spectrum of these tumors in patients with AD. Methods The clinical information of thymic amyloidosis and MALT lymphoma surgically treated at Kanagawa Cardiovascular and Respiratory Center, and Yokohama City University Hospital from January 2010 to December 2019 were reviewed. The correlation between resected thymic tumors at same period and ADs were also investigated. Results There were 5 cases of thymic amyloidosis and MALT lymphoma. ALL cases had coexistent ADs (4 SjS, 1 SSc). The median age was 66 (38–76) year-old, and 4 of the patients were female. Three cases had already diagnosed as ADs before detection of tumors. Only SSc case was received preceding steroid medication. Two cases diagnosed as SjS at the same time of the operation. The median maximum tumor diameter was 70 mm. On chest computed tomography (CT), tumors contained solid part and some cystic part at various rated. Calcification was recognized with appearance of amyloid deposition. All patients were surgically treated with total thymectomy and they are alive without recurrence. At the same period, there were 163 resected thymic tumors, including amyloidosis, MALT lymphoma, thymoma, thymic cancer, neuroendocrine tumor and so on. Among them, nine patients (5.5%) had ADs. There was a correlation between ADs and thymic MALT lymphoma/amyloidosis (P<0.001). Conclusions We propose a process for tumorigenesis of thymic MALT lymphoma and amyloidosis. Underlying AD causes persistent and chronic inflammatory reactions. In this theory, ADs, especially SjS, might be important underlying conditions in formation of rare tumors. When the clinician encounters a patient with AD, routine chest CT is recommended and may provide thymic tumors. Conversely, in case of mediastinum tumor, screening test for AD is also recommended.

A systematic review and meta-analysis of thymic mucosa-associated lymphoid tissue lymphoma

“…These outcomes may further confirm that thymic MALT lymphoma is an indolent disease. However, MALT lymphoma in multiple non-lymphoid organs may lead to a worse prognosis, which was indicated in our study and another study by Aria et al ( 76 ).…”

“…The regimen of systemic treatment varied. For indolent and low-grade SS-associated lymphoma, rituximab (RTX), an anti-CD20 drug, may achieve a good effect (75). Three patients in the study received RTX only after surgery, and they all had good prognoses (7,11,42).…”

Thymus and lung mucosa-associated lymphoid tissue lymphoma with adenocarcinoma of the lung: a case report and literature review

“…The majority of reported cases of MALT lymphoma with amyloid deposition have exhibited an indolent clinical course [ 24 ]. In addition, such nodules of amyloid deposition may also relate to preexisting chronic inflammatory conditions or may be associated with autoimmune conditions such as SS, which produce excess immunoglobulin light chains that misfold and form deposits [ 28 , 29 ].…”