159 Neoplastic Lymphadenopathy: Hodgkin Lymphoma

Clinical Presentation

26-year-old man with chest discomfort

Radiologic Findings

PA (Fig. 159.1) and lateral (Fig. 159.2) chest radiographs demonstrate a large lobular anterior mediastinal mass that extends to both sides of midline, but predominantly to the right. Contrast-enhanced chest CT (mediastinal window) (Figs. 159.3, 159.4) reveals a large mediastinal soft-tissue mass of irregular lobular borders, which occupies the anterior mediastinum; encases the left brachiocephalic vein, superior vena cava, and ascending aorta; partially encases the right upper lobe bronchus; and produces an irregular margin with the adjacent right upper lobe. Note associated right paratracheal lymphadenopathy (Fig. 159.3).

Diagnosis

Hodgkin Lymphoma

Differential Diagnosis

• Non-Hodgkin Lymphoma

• Metastatic Mediastinal Lymphadenopathy; Lung Cancer, Extrathoracic Malignancy

• Thymoma, Invasive

• Thymic Malignancy

Fig. 159.1

Fig. 159.2

Fig. 159.3

Fig. 159.4

Discussion

Background

The lymphomas are a heterogeneous group of malignant neoplasms of the cells of the immune system characterized by proliferation and enlargement of lymph nodes and secondary lymphoid tissues. Non-Hodgkin lymphoma is the most frequent lymphoma and accounts for approximately 75% of cases, while Hodgkin lymphoma accounts for approximately 25% of lymphomas. However, mediastinal involvement by lymphoma is much more common in patients Hodgkin lymphoma than in those with non-Hodgkin lymphoma. The most common cell type of mediastinal Hodgkin lymphoma is nodular sclerosis. The most common mediastinal non-Hodgkin lymphoma is diffuse large B-cell lymphoma (which, together with follicular lymphoma, accounts for over 50% of all non-Hodgkin lymphomas), although lymphoblastic lymphoma and adult T-cell lymphoma characteristically manifest as large mediastinal masses. The latest WHO classification of lymphoma is complex and consists of over 20 subtypes based on cell of origin (B or T cell), morphologic features, and immunophenotypic characteristics.

Etiology

The etiology of lymphoma is unknown. The increasing incidence of non-Hodgkin lymphoma has been in part attributed to the growing elderly population and the HIV epidemic. Various forms of immunosuppression have been linked to extranodal lymphoma.