Presentation
Chest pain.
Patient Data
There is enlargement of the right hilum and right and left paratracheal stripes. The lungs and pleural spaces are clear. Heart size is normal. No pneumothorax or subdiaphragmatic free gas.
There is a large, infiltrative, malignant-appearing lesion which appears to be centered in the anterior and superior right mediastinum. The lesion appears to be invading the inferior aspect of the superior vena cava which appears either occluded or subject to a very high-grade stenosis secondary to tumor thrombus here. SVC obstruction is present with signs of collateral circulation hypertrophy. The lesion also appears to be invading into the right atrium. It exerts quite marked compressive mass effect on the structures of the superior mediastinum compressing in particular the right main pulmonary artery, which has a maximum AP dimension of approximately 4 mm at its narrowest point as a result. There is some mild compression exerted on the carina and the right and left main bronchi. The aorta is displaced from right to left.
There is bland thrombus present in the superior vena cava above the tumor thrombus and bland thrombus present within the brachiocephalic vein. The bland thrombus extends into the external and anterior jugular veins on the left. There is bland thrombus in the inferior aspect of the IJV on the right.
The remainder of the chest and neck are unremarkable.
Case Discussion
This mediastinal tumor has aggressive features and causes SVC syndrome. At this age group, a germ cell tumor or sarcoma should be considered among the differentials. Lymphoma is felt less likely due to the invasive/compressive behavior over the adjacent mediastinal structures. Thymic carcinoma is a less likely differential for this age group.
CT-guided core biopsy was performed:
MICROSCOPIC DESCRIPTION: The sections of core biopsy show connective tissue infiltrated by sheets of discohesive atypical cells with scant cytoplasm and irregular intermediate to large nuclei, accompanied by small lymphocytes. No glandular formation, intracytoplasmic vacuoles or pigment are seen. The cells exhibit nuclear fragility and show crush and streaking artefact.
IMMUNOHISTOCHEMICAL PROFILE:
- CD20 - Positive diffuse staining in large cells
- PAX-5 - Positive in large cells
- CD3 - Negative in large cells, positive in reactive small T cells
- CD5 - Negative in large cells, positive in reactive small T cells
- bcl-2 - Positive
- TdT - Negative
- MUM-1 - Positive in large cells
- bcl-6 - Positive in 30% of large cells
- CD10 - Negative
- Ki67 - Positive in 80-90% of large cells
- cMyc - to follow
- AE1/AE3 - Negative
DIAGNOSIS: Anterior mediastinal mass, core biopsy: Diffuse large B cell lymphoma, activated B cell phenotype.
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