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Thymic and Pulmonary Mucosa-Associated Lymphoid Tissue Lymphomas

2013; Elsevier BV; Volume: 95; Issue: 3 Linguagem: Inglês

10.1016/j.athoracsur.2012.08.067

1552-6259

Takashi Muramatsu, Yoko Tanaka, Ryota Higure, Misato Iizuka, H. Hata, Motomi Shiono,

Chronic Lymphocytic Leukemia Research

A 52-year-old woman with no history of autoimmune disease was found to have a mediastinal tumor and focal airspace opacity in the right lung. Tissue diagnosis was obtained by resection of the mediastinal tumor and open fine needle aspiration of the right pulmonary tissue through a median sternotomy. Histopathologic examination and immunohistochemistry of the thymus tumor and cytologic analysis of the pulmonary tissue were both consistent with mucosa-associated lymphoid tissue (MALT) lymphoma. This case suggests that multiorgan MALT lymphoma can also develop in the absence of an autoimmune disease such as Sjogren's syndrome. A 52-year-old woman with no history of autoimmune disease was found to have a mediastinal tumor and focal airspace opacity in the right lung. Tissue diagnosis was obtained by resection of the mediastinal tumor and open fine needle aspiration of the right pulmonary tissue through a median sternotomy. Histopathologic examination and immunohistochemistry of the thymus tumor and cytologic analysis of the pulmonary tissue were both consistent with mucosa-associated lymphoid tissue (MALT) lymphoma. This case suggests that multiorgan MALT lymphoma can also develop in the absence of an autoimmune disease such as Sjogren's syndrome. Mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal low-grade B-cell lymphoma that occurs in MALT usually found in Waldeyer's ring, salivary glands, thyroid gland, lungs, gastrointestinal tract, and skin. MALT lymphoma rarely involves the thymus gland. We recently treated a case of two simultaneous MALT lymphomas in the thymus gland and the right lung. The tumors were an incidental finding, and we hereby highlight our experience in this case. An asymptomatic 52-year-old woman had a routine chest roentgenogram as part of a medical checkup, which showed an anterior mediastinal shadow protruding into the right thoracic cavity. Her medical history was unremarkable except for rheumatic fever when she was in her 20s. Subsequent computed tomography (CT) of the chest on an outpatient basis highlighted two lesions: a well-circumscribed mass with several lobulated cysts on the right anterior surface of the pericardium (Fig 1A) and a focal airspace opacity in the right lower lobe (Fig 1B). No particular abnormalities were observed on routine preoperative blood tests which included tumor markers. The anterior mediastinal mass was approached through a median sternotomy. During the operation, the tumor was found to originate from the thymus gland and to be in contact with the left brachiocephalic vein and the pericardium, but resection was performed with ease. The right parietal pleura was incised to gain access to the right pulmonary lower lobe lesion. However. no resectable mass was found at this site. where the focal airspace opacities were originally seen on the chest CT scan. Fine needle aspiration was performed for cytologic assessment instead. Macroscopically, the thymic mass measured 13.5 × 8.0 × 3.0 cm (Fig 2) and was mostly well circumscribed, with elastic, hard, and solid sites, and containing several cystic lesions, with the largest being 4.5 cm, containing clear to serosanguinous fluid. Histopathologic assessment revealed that the lymphoid cells were constricted in the nuclei, and there were many irregular centrocyte-like cells (CCL) with occasionally bright cytoplasm (Fig 3A). The remaining thymic epithelial tissue showed infiltration of CCL cells. Immunohistochemical study showed that these CCL cells stained positive for CD20 antibodies. Cytologic analysis of the fine needle aspirate of the right pulmonary lower lobe focal airspace opacity showed a proliferation of lymphoplasmacytic cells (Fig 3B). These findings confirmed a diagnosis of MALT lymphoma of the thymus and pulmonary right lower lobe.Fig 3(A) Histologic findings of the anterior mediastinal tumor, there are many centrocyte-like cells (hematoxylin and eosin staining; ×60). (B) Cytotechnologic analysis of the focal airspace opacities of the right lower lobe, showing proliferation of lymphoplasmacytic cells. (Papanicolaou staining; ×100).View Large Image Figure ViewerDownload (PPT) The postoperative course was uncomplicated, and the index patient was discharged home on postoperative day 4. She has since been followed up as an outpatient with no signs of any disease progression of the pulmonary MALT lymphoma and no recurrence of the thymus MALT lymphoma. MALT lymphoma was only recently first reported in the thymus gland [1Isaacson P.G. Chan J.K. Tang C. Addis B.J. Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue arising in the thymus: a thymic lymphoma mimicking myoepithelial sialadenitis.Am J Surg Pathol. 1990; 14: 342-351Crossref PubMed Scopus (139) Google Scholar], mostly in women ranging from 40 to 60 years of age, and with a predominantly higher incidence in Far East Asia than in the white population [2Shimizu K, Yoshida J, Kakegawa S, et al. Primary thymic mucosa-associated lymphoid tissue lymphoma: diagnostic tips. J Thorac Oncol;5:117–21.Google Scholar]. It is believed that the etiology of MALT lymphoma is associated with continuous stimulation of antigens to the B-lymphocyte system, and it is frequently associated with autoimmune diseases or chronic inflammatory disorders such as Helicobacter pylori gastritis [2Shimizu K, Yoshida J, Kakegawa S, et al. Primary thymic mucosa-associated lymphoid tissue lymphoma: diagnostic tips. J Thorac Oncol;5:117–21.Google Scholar, 3Nagasaka T. Lai R. Harada T. et al.Coexisting thymic and gastric lymphomas of mucosa-associated lymphoid tissues in a patient with Sjogren syndrome.Arch Pathol Lab Med. 2000; 124: 770-773PubMed Google Scholar]. MALT lymphoma in the thymus gland in particular has been associated with autoimmune diseases, predominantly Sjogren's syndrome, with an observed frequency of more than 70% [2Shimizu K, Yoshida J, Kakegawa S, et al. Primary thymic mucosa-associated lymphoid tissue lymphoma: diagnostic tips. J Thorac Oncol;5:117–21.Google Scholar]. The typical reported CT findings in thymic MALT lymphomas are a clear tumor outline, relatively even internal density, and a tendency for cyst formation [4Yi J.G. Kim D.H. Choi C.S. Malignant lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) arising in the thymus: radiologic findings.AJR Am J Roentgenol. 1998; 171: 899-900Crossref PubMed Scopus (22) Google Scholar]. The thymus tumor in our case fulfilled all these radiologic characteristics. The exact histopathologic relationship between the thymus and pulmonary MALT lymphomas in our case is not entirely clear, and a possibility of metastasis from one primary tumor cannot be excluded. However, thymic MALT lymphomas are normally slow to progress, and we are not aware of any case reports to date describing any metastasis to multiple organs [1Isaacson P.G. Chan J.K. Tang C. Addis B.J. Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue arising in the thymus: a thymic lymphoma mimicking myoepithelial sialadenitis.Am J Surg Pathol. 1990; 14: 342-351Crossref PubMed Scopus (139) Google Scholar, 5Sunada K. Hasegawa Y. Kodama T. et al.Thymic and pulmonary mucosa-associated lymphoid tissue lymphomas in a patient with Sjogren's syndrome and literature review.Respirology. 2007; 12: 144-147Crossref PubMed Scopus (21) Google Scholar]. The incidence of coexisting MALT lymphoma in two different organs is extremely rare, and only one case report has been published on thymic and pulmonary MALT lymphoma in 2007 [5Sunada K. Hasegawa Y. Kodama T. et al.Thymic and pulmonary mucosa-associated lymphoid tissue lymphomas in a patient with Sjogren's syndrome and literature review.Respirology. 2007; 12: 144-147Crossref PubMed Scopus (21) Google Scholar]. Before that, Nagasaka and associates [3Nagasaka T. Lai R. Harada T. et al.Coexisting thymic and gastric lymphomas of mucosa-associated lymphoid tissues in a patient with Sjogren syndrome.Arch Pathol Lab Med. 2000; 124: 770-773PubMed Google Scholar] reported on simultaneous thymic and gastric MALT lymphomas, and they concluded that the thymic and pulmonary MALT lymphomas occurred independently, on the basis of a difference in monoclonal gene rearrangement between the two tumors. Furthermore, both patients in these cases had a history of Sjogren's syndrome. Our case suggests that multiorgan MALT lymphoma can develop in the absence of an autoimmune disease. According to the current literature, surgical treatment seems to be the standard of care for MALT lymphomas involving the thymus gland because of the diagnostic difficulty based on radiologic findings or cytologic analysis of limited specimens from percutaneous fine needle aspiration. In some cases, adjuvant chemotherapy has been performed after operation [2Shimizu K, Yoshida J, Kakegawa S, et al. Primary thymic mucosa-associated lymphoid tissue lymphoma: diagnostic tips. J Thorac Oncol;5:117–21.Google Scholar]. In our case, the pulmonary MALT lymphoma was unresectable. Therefore, close follow-up is necessary to ensure that appropriate treatment can be introduced when required.