When to suspect a thymoma: clinical point of view.

The thymus plays a crucial role in the development of immune system, regulating the maturation, selection and migration of T lymphocytes. Alterations in lymphatic content and structure of the thymus are observed in many autoimmune diseases. Moreover, changes of the epithelial component may cause the development of thymic tumours. Thymoma is a rare epithelial tumor of the anterior mediastinal compartment with a wide spectrum of clinical presentations. The causes of thymoma are still unknown and several hypotheses have been formulated. Thymomas show a variable course causing, frequently, a prolonged clinical history. The presence of metastasis at the time of diagnosis is very uncommon. Even if about 30% of the patients with thymoma are asymptomatic, they may have local symptoms (such as cough, pain, hoarseness, and dyspnea) or paraneoplastic disorders. The role of immune system in the pathogenesis of these tumors and related paraneoplastic syndromes is not completely clear. A clinical diagnosis, especially if the first manifestation is a thymoma-associated paraneoplastic disease, is not always easy and should be supported by an appropriate imaging in order to guide the proper management for each patient. In this article, we would like to give an overview of the local and systemic clinical manifestations, which can be found in patients affected by thymoma.