Thymic lymphoma usually manifests as a homogeneous, round mass with soft tissue density and without calcification. Lymphadenopathy is infrequently detected on chest radiography but often is seen on CT. Sarcoidosis. They include irregular tumor margins; invasion of surrounding mediastinal fat, vascular structures, or chest wall; and irregular interface with the adjacent lung. The presence of enlarged mediastinal lymph nodes may suggest the diagnosis. Anterior Mediastinal Mass. Clinically, an anterior mediastinal mass … Configuration of the interface of the mass with adjacent lung is sometimes helpful. A, The lateral chest radiograph reveals increased opacity in the normally clear retrosternal space (lower arrow) and a presternal soft tissue mass (upper arrow). Bilaterality of abnormality in proximity to the thoracic midline suggests a mediastinal origin. No radiologic features differentiate thymic carcinoid from thymic carcinoma. 16-11), in contrast to most other causes of mediastinal masses, which usually manifest as a single mass. Mediastinal compartments. In some cases, imaging features enable the radiologist to make a specific diagnosis. Anterior mediastinal masses generally arise from these structures. Acquired thymic cysts are most often associated with Hodgkin’s disease after radiation therapy. Thorough pathologic sampling is recommended to exclude small foci of immature tissue, other germ cell tumors, or carcinoma. Thyroid abnormalities account for most thoracic inlet masses in adults (Box 16-6). Characteristic CT imaging features include a well-defined, round, or oval mass, usually of homogeneous soft tissue density, that is located within the anterior mediastinum (Fig. It is anticipated that this system will improve lesion localization, help generate a focused differential diagnosis, and assist in tailoring biopsy and treatment plans. Rebound thymic hyperplasia may be seen in patients who have been treated with chemotherapy. Whereas anterior mediastinal masses from lymphoma typically demonstrate well-defined margins, invasion of adjacent lung parenchyma may result in irregular margins. In patients with prior neck exploration and continued primary hyperparathyroidism, the incidence of mediastinal adenoma is 47%, and 17% of such glands cannot be reached from a neck incision. In some cases, imaging features enable the radiologist to make a specific diagnosis. Compared with single-detector spiral CT scanners, multidetector-row CT scanners are associated with improved spatial resolution, faster scanning, improved vascular enhancement, and higher-quality multiplanar reformation images. Surgical excision of teratomas and dermoid cysts is usually curative. Contrast-enhanced CT is preferred for the evaluation of middle mediastinal masses, especially when you suspect a vascular abnormality. Thymic cysts may be congenital or acquired. It is helpful to identify the location of the mass since this significantly reduces the breadth of the … B, Axial CT image of the chest (filmed using soft tissue windows) shows an anterior mediastinal mass (black arrows) and multiple, unilateral pleural masses (curved arrows). In many cases, non–contrast-enhanced CT is sufficient, but in others, contrast-enhanced CT can provide important information concerning enhancement of the mass and its relation to adjacent vascular structures. C, Axial, contrast-enhanced CT image at the level of the aortic arch shows the large, substernal component of the mass (arrows), which displaces the ascending aorta (A) and superior vena cava (S) posteriorly. 16-2). The mass contains foci of thyroid tissue that demonstrate intense enhancement and foci of low attenuation consistent with cysts. Multiple masses within known anatomic lymph node sites suggest lymphadenopathy. Anterior mediastinal masses consist of the 4 "T's" (Terrible lymphadenopathy, Thymic tumors, Teratoma, Thyroid mass… They may extend inferiorly into the anterior, middle, and posterior compartments of the mediastinum. Age: young patients, usually in third decade, Gender: malignant germ cell neoplasms have marked male predominance, Heterogeneous, predominately cystic mass with solid components, Presence of fat is suggestive; identification of a tooth, although rare, is diagnostic. Posterior mediastinal mass. Only 10% of lymphomas which involve the mediastinum are primary (i.e. A small percentage of these tumors contain calcification. In contrast, most other thymic abnormalities appear as a discrete mass rather than as uniform glandular enlargement. 2. Radiology of Mediastinal Masses Evaluation of the mediastinum is an important part of the interpretation of a chest x-ray (CXR). Imaging features vary, ranging from a single, spherical soft tissue mass in the anterior mediastinum to a large, lobulated mass representing a conglomeration of lymph nodes. Figure 16-7 Lymphoma. 3. FDG-PET and FDG-PET/CT play important roles in staging lymphoma and in assessing the response to therapy. B, Axial, contrast-enhanced CT image reveals a round, anterior mediastinal mass with a partially calcified rim (right arrow) and a fat-fluid level (down arrow). Most thymomas are benign lesions confined within a fibrous capsule, but about 30% of thymomas are more aggressive and demonstrate invasion through the fibrous capsule. Radiologic examination of a mediastinal mass usually can narrow the differential diagnosis to two or three likely candidates. An anterosuperior mediastinal mass can be caused by neoplastic and non-neoplastic pathology. Mediastinal masses may be nonvascular or vascular masses and represent congenital anomalies, infections, benign and malignant neoplasms, and pseudomasses. A fat-fluid level is seen in 10% of cases and is highly specific for teratoma (Fig 16-8). There are a number of clinical conditions associated with thymoma, including myasthenia gravis (MG), pure red cell aplasia, and hypogammaglobulinemia. 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