[Mesenchymal tumors of the mediastinum]

Benign lesions of the mediastinum

Mediastinal tumours represent a heterogeneous group of entities derived from the manifold structures located in or adjacent to the mediastinum. Due to the occurrence of some of these tumours in characteristic mediastinal compartments, an anatomical subdivision of the mediastinum in the prevascular (anterior), visceral (middle), and paravertebral (posterior) is helpful for the differential diagnosis. Benign anterior mediastinal tumours linked to an enlargement of the thymic gland mainly consist of thymic cysts and several types of thymic hyperplasia: true thymic hyperplasia, rebound hyperplasia, lymphofollicular hyperplasia, and so-called thymic hyperplasia with lymphoepithelial sialadenitis (LESA)-like features. Mature teratomas, ectopic (para)thyroid tissue, and benign thymic tumours such as thymolipoma or thymofibrolipoma represent further typical tumours of the anterior mediastinum. Pericardial, bronchogenic, or oesophageal duplication cysts predominate in the middle mediastinum, whereas neurogenic tumours and myelolipomas are characteristic findings in the posterior compartment. Vascular tumours, lipomas, adenomatoid tumours, Castleman disease, or mediastinitis are further examples of less frequent tumours or tumorous lesions affecting the mediastinum. This review focuses on benign mediastinal lesions with an emphasis on benign tumours of the thymus. Besides histology, characteristic epidemiological and clinical aspects prerequisite for the correct diagnosis and patient management are discussed.

[Mediastinal pseudotumor-necrotizing and sclerosing mediastinitis with pseudomembranes]

Mediastinal tumors present a rather rare phenomenon with a variety of underlying causes. Important differential diagnoses include benign and malignant tumors as well as idiopathic sclerosing mediastinitis and parasitic infection.Here, we present the case of a mediastinal pseudotumor with compression of the superior vena cava in a young adult male who spent several years abroad in Brazil. Clinicians suspected either a mediastinal lymphoma, malignant mesenchymal tumor, teratoma, sarcoidosis, or tuberculosis. Biopsy tissue failed to provide a definite diagnosis. The subsequently resected mediastinal mass showed a necrotizing, granulomatous inflammation with prominent eosinophilia and sclerosis. Membranous structures were detected in the necrotic areas, which presented as collagen bundles ultrastructurally. Therefore, these membranes were proven to be constituents of lipid pseudomembranes. Consequently the lesion shows characteristics of sclerosing mediastinitis next to characteristics of adipose tissue necrosis with lipid pseudomembranes. Parasitic infection could not be proven.

Utility and Safety of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in the Diagnosis of Isolated Mediastinal Masses

Background

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a valuable tool for diagnosing pulmonary disease due to its efficiency and safety. We retrospectively analyzed patients with mediastinal masses who underwent diagnostic EBUS-TBNA at Shanghai Chest Hospital, and evaluated the clinical accuracy of EBUS-TBNA in the diagnosis mediastinal masses.

Method

From 2009 and 2014, patients who received EBUS-TBNA to diagnose a isolated mediastinal mass were enrolled. Clinical follow-up was performed to ascertain the patient’s final diagnosis.

Results

Forty-six patients were enrolled in this study. Thirty-seven were diagnosed with an oncologic disease, 3 were diagnosed with a mediastinal infection, and 2 were found to have a mediastinal goiter. The overall sensitivity, specificity, positive predictive value, negative predictive value, diagnostic yield was 63.6%, 100%, 100%, 42.9%, and 71.4%, respectively.

Conclusion

EBUS-TBNA is a safe and effective means of diagnosing mediastinal masses.