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.

Epidemiology

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

Radiographic features

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 adenopathylymphadenopathy or a mass on a chest radiograph
• no previous extra-thoracicextrathoracic lymphoma
• no evidence of extra-thoracicextrathoracic lymphoma or lymphatic leukaemia at the time of diagnosis
• there is nono extrathoracic disease outside of the thorax for least three months following the 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 lymphoma
• pulmonary involvement with satellite nodes (hilar or mediastinal)
• multiorgan involvement by lymphomatoid granulomatosis, the clonal nature of which is controversial

Treatment and prognosis

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

See also

• paediatric mediastinal masses