Pulmonary leukemic infiltratation

Pulmonary leukemic infiltrations correspond to extravascular collections of leukemic cells in the lung parenchyma. On imaging, although having a broad and nonspecific pattern of presentation, is commonly seen as thickening of the bronchovascular bundles and interlobular septa.

Epidemiology

They can be found in the lungs in around 24-64% of patients with leukemia on autopsy.  Multiple studies have shown no significant difference in the incidence of the leukemic infiltrates among the four major types of leukemia .

Pathology

The leukemic infiltration is only called by its own, as a direct manifestation of leukemia, in the absence of leukamia-related complications that could be attributed as a cause (eg.: superimposed infection, alveolar hemorrhage, or pulmonary venous congestion) .

Histologically, there is atypical lymphocyte infiltration along the interstitium and alveolar spaces.

Radiographic features

It can have a variety of nonspecific radiographic appearances.

Plain radiograph

Most infiltrates do not appear on chest radiographs .

CT

Pulmonary consolidations in a variety of patterns have been described, including alveolar, interstitial, mixed, and peribronchial/perivascular patterns .  There is a general tendency for abnormalities to involve the perilymphatic interstitium .

Other reported findings include :

• common
  • thickening of bronchovascular bundles: ~ 80% 
    • both smooth or nodular thickening have been described
  • prominence of peripheral pulmonary arteries: ~ 80% 
  • non-lobular and non-segmental ground-glass opacities: ~90% 
• uncommon
  • pulmonary nodules
    • peribronchovascular, centrilobular, or random in distribution
    • usually of small size and in a small number
  • focal homogeneous pulmonary opacities 

Differential diagnosis

Due to the variable appearance on CT, the differential diagnosis based on imaging may be broad :

• pulmonary edema
• pulmonary hemorrhage
• pulmonary infection

See also

• pulmonary lymphoma