Presentation
Chest pains associated with nonproductive cough.
Patient Data
Chest radiographs show a lobulated soft tissue density obscuring the aortic knob and extending down to the level of the left atrial appendage. The mass appears to be located in the anterior mediastinum on the lateral view.
There is an intensely enhancing, non-calcified, lobulated mass, measuring approximately 2.4 x 5.9 x. 6.7 cm (AP x W x CC) in the left anterior mediastinum at the level of the aortic arch extending to the left lateral aspect of the main pulmonary artery.
Excision of the anterior mediastinal mass was done. Histopathologic examination revealed nodal tissue with proliferation of follicles characterized by regressively transformed germinal centers. There is tight concentric layering of lymphocytes at the periphery of the follicles resulting in an onionskin-like appearance. The follicles showed marked vascular proliferation and hyalinization of the germinal centers. The intrafollicular stroma is otherwise prominent, with numerous hyperplastic vessels and admixture of plasma cells, eosinophils, and immunoblasts. Associated vascular proliferation is also present in the surrounding soft tissue. The histologic features were compatible with Castleman disease, hyaline vascular type (angiofollicular lymph node hyperplasia).
Case Discussion
Castleman disease is a rare, benign disorder of the lymph nodes that should be included in the differential diagnosis of anterior mediastinal masses. It is a lymphoproliferative disorder and is also known as angiofollicular lymph node hyperplasia, benign giant lymphoma, giant lymph node hyperplasia, and follicular lymphoreticuloma 1-3. It can occur anywhere in the body wherever there are lymph nodes. Approximately 70% of the cases are located in the thorax, 14% in the neck, 12% in the abdomen and 4% in the axilla 4.
The lesions in Castleman disease are predominantly of two histologic types: the hyaline vascular type and the plasma cell type. The majority of these lesions are of the hyaline vascular type, which accounts for approximately 90% of cases and is most often a localized disease 1.
On CT, the classic appearance of hyaline vascular Castleman disease is that of a solitary enlarged lymph node or localized nodal masses that demonstrate homogeneous intense enhancement after contrast material administration 5.
There are three patterns of involvement, including a solitary noninvasive mass (most common: 50% of cases), a dominant infiltrative mass with associated lymphadenopathy (40% of cases), and matted lymphadenopathy without a dominant mass (10% of cases) 6.
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