Aims: This case reports is about a patient with diagnosis of thymoma with intercurrent infection with Toxoplasma gondii. The state of immunosuppression caused by thymoma had probably facilitaded the development of an infection with Toxoplasma gondii, that determined lymph nodes involvement and symptoms, appearing like lymphoproliferative disease. Presentation of the Case: A 57-year-old woman presented with intense night sweats, fatigue, dyspnea on moderate effort, multiple superficial enlarged lymph nodes, and fever with shivering. Blood tests showed marked leukocytosis with lymphocytosis and eosinophilia, normal hemoglobin and platelet counts, increased ESR (40 mm) and LDH (606 U/L). The search for anti-Toxoplasma IgM antibodies was positive and the serum protein electrophoresis showed increased acute phase proteins. Suspicion of lymphoproliferative disease became stronger after the execution of CT and PET. In agreement with the thoracic surgeon, we decided to perform biopsy of the mediastinal mass in order to confirm diagnosis. The histological examination showed the presence of a thymoma. Case Study Isabella et al.; BJMMR, 7(5): 425-431, 2015; Article no.BJMMR.2015.349 426 Discussion: When the patient first came to our department, given the physical examination and the reported symptoms, the case seemed easy to solve. Suspicion of lymphoproliferative disease became stronger after the execution of CT and PET. Nevertheless, the diagnostic process was complicated and required two surgical procedures over a short period time, before the thymectomy itself. Conclusion: This patient was affected by two rare medical conditions involving the lymph node system. The collaboration between the various specialists allowed us to exclude the hypothesis of lymphoproliferative disorder and to reach the correct diagnostic conclusions. The correct diagnosis has allowed appropriate treatment for resolution of thymoma.