Peripheral T-Cell Lymphocytosis as A Rare Presentation in Thymoma: A Case Report

Background: Distant liver metastasis and peripheral T-cell lymphocytosis are rare conditions in malignant thymoma explained in the current study for the first time. Case presentation: A 66–year-old female was admitted for progressive dyspnea. Paraclinical imaging revealed enlarged mediastinum, conglomerated lymphatic mass, bilateral pleural effusion, and neoplastic filtrations in the liver. Her complete blood count showed lymphocyte dominant (73.4%) leukocytosis (17100 per ml). Therefore, bone marrow aspiration/biopsy was performed, which revealed polyclonal T-cells. She was finally diagnosed with malignant thymoma, underwent chemotherapy, and dramatically responded as the symptoms relieved, the metastasis shrunk, and the lymphocytosis resolved. Conclusion: T-cell lymphocytosis spillover is a rare paraneoplastic presentation of thymoma that may show the tumor's aggression; however, well-responded to chemotherapy only approach. Peripheral T-cell lymphocytosis should be considered in thymomas as it may contribute to a better understanding of the thymoma complexity and pathogenesis