Secondary pulmonary lymphomas refer to pulmonary involvement with lymphoma when the condition is not limited to the lung and has mediastinal lymph node involvement or evidence of extrathoracic dissemination for at least three months after the initial diagnosis. This is a more common form of pulmonary lymphoma.
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Epidemiology
The incidence of involvement of the lung at initial presentation is reported to be 12% of patients with Hodgkin’s disease and 4% of those with non-Hodgkin’s lymphoma 1. With non-Hodgkin lymphoma, pulmonary involvement may occur in ~30% (range 25-40%) as a site of relapse after treatment 1,4.
Pathology
The pathogenesis of secondary pulmonary lymphoma can be rather variable and depends on the type of primary lymphoma 5. While all forms of lymphoma may secondarily involve the lungs, the mature B-cell neoplasms may be the most frequent 5.
On histopathology, secondary pulmonary lymphoma and primary pulmonary lymphoma show identical morphological features 5.
Radiographic features
CT
Radiographic appearances can be variable and can mimic that of primary pulmonary lymphoma 4. It may have a lymphangitic, nodular and/or alveolar pattern.
Individual features are non-specific but reported manifestations include:
- peribronchovascular thickening
- small peribronchovascular nodules
- airspace consolidation with air bronchograms: more common with NHL 5
- large focal mass-like lesions
- in Hodgkin disease, parenchymal involvement is almost always associated with mediastinal and/or hilar lymphadenopathy and there is typically a contiguous spread of disease
In some cases, pleural effusion may be present.
