Composite type A thymoma and diffuse large B-cell lymphoma

Hsin-I Chen^a, Chee-Yin Chai^{a, b}, Shih-Feng Cho^c, Jui-Ying Lee^d, Wan-Tzu Chen^a, Chun-Chieh Wu^a

^a Department of Pathology, Kaohsiung Medical University Hospital and Kaohsiung Medical University, Kaohsiung, Taiwan
^b Department of Pathology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
^c Division of Hematology & Oncology, Department of Internal Medicine, Kaohsiung Medical University Hospital and Kaohsiung Medical University, Kaohsiung, Taiwan
^d Division of Chest Surgery, Department of Surgery, Kaohsiung Medical University Hospital and Kaohsiung Medical University, Kaohsiung, Taiwan

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Abstract

The concurrent occurrence of thymoma and diffuse large B-cell lymphoma in the thymus has not been previously reported. We describe a 74-year-old man who presented with general weakness, neck lymphadenopathy, night sweats, and body weight loss. A right anterior mediastinal mass was found on computed tomography of the chest. The immunohistochemical stains AE1/AE3, CD20, CD3, and MUM-1 confirmed the different components of the mediastinal tumor. A heavy-chain gene clonality assay and light-chain gene clonality assay confirmed the B-cell clonality of the mediastinal tumor and neck lymph node. The patient had received a complete course of chemotherapy, and the result of positron emission tomography–computed tomography showed complete remission. The pathologic report of this mass revealed composite type A thymoma and diffuse large B-cell lymphoma. If concurrent or composite thymoma and lymphoma are suspected, a thorough examination of the thymoma with a combination of ancillary studies is recommended to rule out the possibility of concurrent lymphoma.

keywords

Clonality assay; Composite tumor; Immunohistochemical stain; Lymphoma; Thymoma