Diagnosis:

Non-Hodgkin's Lymphoma
(diffuse large B-cell type)
 

Radiologic Findings


 
PA chest radiograph shows moderate cardiomegaly.

 Contrast-enhanced CT scans show large amount of pericardial effusion, bilateral pleural effusions, homogenenous soft tissue mass involving the pericardial space, and several pulmonary nodules.
 

 

Brief Review


Malignant lymphoma can present as a mass in anterior, superior, or middle mediastinum. It may appear in this area as part of the manifestations of the disseminated process or as a primary mediastinal disease. The majority of malignant lymphoma presenting as primary mediastinal neoplasm falls into the following three categories:
Hodgkin's lymphoma, lymphoblastic lymphoma, and large cell lymphoma, in order of frequency.

 Intrathoracic disease is more common in Hodgkin's disease (HD) than non-Hodgkin's lymphoma (NHL). All of the mediastinal nodal groups except the anterior diaphragmatic  (paracardiac) and posterior mediastinal nodes are more frequently involved with HD than NHL. Intrathoracic disease of NHL may follow the patterns described for HD. However, the contiguity of nodal disease typical for HD is frequently absent in NHL. Involvement of the paratracheal and/or prevascular nodal groups is the most common. These are followed by subcarinal nodes, cardiophrenic angle nodes, internal mammary nodes, and posterior mediastinal nodes. In NHL, pulmonary or pleural lesions may be seen without mediastinal or hilar adenopathy. However, it is more common to find some manifestations of mediastinal disease when the lungs are involved.

 
Mediastinal large cell lymphomas can present as a mass in the thymus with or without lymph node involvement. Large cell lymphoma of mediastinum is usually restricted to the intrathoracic region at the time of initial presentation. The tumor has grossly invasive features; extension into pericardium, pleura, lung, sternum, and chest wall is common and presentation with superior vena cava syndrome is frequent. Of tumors studied with cell markers, the majority has been found to have B-cell nature, but T-cell malignancies are also present.

 On CT scan, the enlarged nodes in any of the malignant lymphomas may be discrete or matted together, and their edges may be well- or ill-defined. In general, they show only minor enhancement. Low density resulting from cystic degeneration may be seen in both Hodgkin's and non-Hodgkin's lymphoma. In a study of radiologic findings of primary mediastinal large-B-cell lymphoma in 43 patients, all but one lesion arouse in the anterior mediastinum, On CT scan, large and lobulated anterior mediastinal masses were visible, averaging 10-cm in diameter. Low attenuation areas of necrosis within the mass were seen in 44%, with calcification in two cases.
Pleural and pericardial effusion were present in about one-third.

 A good response to radiation therapy and chemotherapy is the rule, but in many instances the tumor recurs massively within the chest and spread to other sites, including peripheral lymph nodes. The presence of pleural effusion at presentation is associated with poor outcome.
 

 

References

Rosai J. Mediastinum. In Ackerman's surgical pathology. 8th ed. St Louis: Mosby, 1996:469-473

Shaffer K, Smith D, Kaplan W, et al. Primary mediastinal large-B-cell lymphoma: radiologic findings at presentation. AJR 1996; 167:425-430

North LB, Libshitz HI, Lorigan JG. Thoracic lymphoma. RCNA 1990; 28:745-762

 

 
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