Primary pulmonary lymphoma

Primary pulmonary lymphoma (PPL) refers to a clonal lymphoid proliferation affecting the lungs without any detectable extrapulmonary involvement. It is a much rarer type of pulmonary lymphoma and is most frequently represented by lymphoma of B cell lineage - often marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type.

The diagnosis of primary pulmonary lymphoma requires the following criteria at the time of initial writing (December 2012) ⁶.

• involvement of lung, bronchus or both are involved without evidence of mediastinal adenopathy or a mass on a chest radiograph
• no previous extra-thoracic lymphoma
• no evidence of extra-thoracic lymphoma or lymphatic leukaemia at the time of diagnosis
• there is no disease outside of the thorax for least three months following initial diagnosis within the lung

When the lung is the principal site of lymphoma, the definition also includes:

• multifocal mucosa-associated lymphoid tissue (MALT) non Hodgkin-Hodgkin lymphoma
• pulmonary involvement with satellite nodes (hilar or mediastinal)
• multiorgan involvement by lymphomatoid granulomatosis, the clonal nature of which is controversial

Epidemiology

Primary pulmonary lymphoma is a very rare entity and is thought to only represent only 3-4% of extranodal non Hodgkin lymphoma, <1% of a all non Hodgkin lymphoma, 0.5-1% of all primary pulmonary malignancies ^1-6.

Treatment and prognosis

This entity of lymphoma is thought to carry a comparatively good prognosis ^4-5,5.

See also

• paediatric mediastinal masses