WHO classification scheme for thymic epithelial tumors

A diagnostic

approach to the mediastinal masses. a–c Thymic hyperplasia in a 43-year-old woman (arrows). a Non-contrast-enhanced CT scan reveals a lobulated lesion with smooth margins in anterior mediastinum. b Lesion appears slightly hyperintense on in-phase gradient-echo T1-weighted MR image. c Opposed-phase gradient-echo T1-weighted MR image shows decreased signal intensity within the lesion, confirming presence of fat. d–f Stage II thymoma (WHO type B2) in a 62-year-old woman (arrows). d Non-contrast-enhanced CT scan shows an anterior mediastinal soft tissue mass. e The lesion shows an intermediate signal intensity on in-phase gradient-echo T1-weighted MR image. f There is no substantial decrease in signal intensity relative to in-phase MR image on opposed-phase sequence

A diagnostic

approach to the mediastinal masses. a, b Stage II thymoma (WHO type B1) in a 33-year-old woman who presented with myasthenia gravis. Frontal chest radiograph shows a hilum overlay sign (arrow) of a suggestive anterior mediastinal mass. Contrast-enhanced CT scan confirms the presence of a low-heterogeneous anterior mediastinal mass (arrow). Note the indentation of the arterial trunk pulmonary by the mass. c, d Stage III thymoma (WHO type B2) in a 54-year-old woman. Frontal chest radiograph reveals a lobulated mediastinal mass (arrow) on the right side. Contrast-enhanced CT scan demonstrates an enhanced anterior mediastinal mass (arrow) with infiltration of surrounding fat (open arrow)

A diagnostic

approach to the mediastinal masses. CT is the imaging modality of choice for evaluating staging thymoma. Stage IVa thymoma (WHO type B3) in a 69-year-old woman. a, b Contrast-enhanced CT scan shows a well-circumscribed, flattened soft tissue lesion in the anterior mediastinum with calcification (arrow). Note the lobulated contour of the mass and the loss of the fat plane between the mass and the aorta. Pleural seeding is identified as an enhancing pleura-based nodule (open arrow). c Irregular border between the mediastinal mass and the lung parenchyma (arrowhead) is observed as a sign of locally advanced disease. Note the cellular bronchiolitis in the left lower lobe

A diagnostic

approach to the mediastinal masses. Stage IVa thymoma (WHO type B2) in a 46-year-old man. a Contrast-enhanced CT scan reveals an anterior mediastinal mass (arrows) with irregular contours, homogeneous enhancement and peripheral and central calcification as well as a pleural nodule (open arrow). b On an axial FDG-positron emission tomography (PET) image, the pleural nodule is FDG avid, confirming a drop metastasis. c Image during the surgical resection. d Photomicrograph (haematoxylin-eosin stain) of tissue from the lesion shows roughly equal numbers of epithelial cells (white arrow) and lymphocytes (black arrow) corresponding thymoma WHO type B2

A diagnostic

approach to the mediastinal masses. Axial (a) and coronal multiplanar reconstruction (b) of a non-contrast-enhanced CT scan of a 57-year-old man allergic to iodine with a thymoma. A solid lobulated thymic mass (*) with clumps of calcifications within (arrowhead) is identified. Note the absence of a fat plane between the tumour and the aorta (open arrow). d Coronal T2-weighted MR image shows a typical signal hyperintensity of the tumour lesion (*). c Axial contrast-enhanced fat-suppressed T1-weighted MR image reveals a homogeneously enhanced solid tumour (*) which arises from the thymus. Although MRI demonstrates the presence of fat cleavage plane between ascending aorta and the tumour, a thymoma (WHO type A) with microscopic transcapsular invasion (Masaoka stage II) was confirmed after surgical resection

Synchronous

primary intrapulmonary and mediastinal thymoma-A case report. Chest computed tomographic scan. Figure 1A, 1B An enhanced Chest computed tomographic scan revealed a mass in the anterior segment of the right upper lobe with continuation to some mediastinal swelling lymph nodes. Multiple swelling lymph nodes could be found in the mediastinum. Figure C Three-D reconstruction showed the superior vena cava, whose lumen was unobstructed but deformated under the compression of the mass. Figure 1D, 1E Postoperative enhanced Chest computed tomographic scan images. Figure 1F, 1G Surgical findings of the mediastinal mass. Figure 1H Surgical findings of the intrapulmonary mass. Figure 1I Reconstruction of left brachiocephalic vein to right auricle and reconstruction of right brachiocephalic vein to superior vena cava.