Progressive Granulomatous Pneumonia with Cavitation

Definition: Disease may progress at any infected site. As the lesion enlarges, the central part tends to undergo necrosis. When the inflammation erodes into a bronchus, the infectious necrotic material, which is initially solid, may liquify and be evacuated, either to other bronchi or to the environment, leaving a cavity.

Active stages: This picture of a multilobular consolidation shows central necrosis (between arrows). After liquifaction, this material could be discharged into an airway. Note also the small, white, satellite, centrilobular nodules, which represent past bronchial and bronchiolar spread.

The faint lines (single arrow) represent interlobular septa thought to be widened by edema. A centrilobular nodule lies just to the left of the arrow. Note that the septal lines surround the nodule to form a polygon that defines the lobule.

 

 

CT correlations: This CT from another patient shows some of the changes described above in the slice of lung.

 

The oldest lesion is an irregular, mass-like consolidation with central cavitation anteriorly on the right. Several other focal consolidations, one cavitary and two bordering the fissure, are also present. Architectural distortion about the large cavity, and focal retraction of the major fissure adjacent to a focal consolidation are consistent with fibrosis. These consolidations likely developed from coalescence of centrilobular nodules.

More recent endobronchial spread of tuberculosis is seen as the smaller, branching opacities, which represent diseased bronchi/ioles, and the small centrilobular nodules (2-4 mm), which represent bronchiolar/acinar disease. As these become confluent, larger macronodules may form, as seen as a solitary nodule in the left upper lobe.

 

Note also the bronchi in the medial RUL, which have thickened walls and dilated lumens consistent with bronchiectasis [1].

 

Histologic correlations: A low-power view of an entire histologic section shows pleura at the top.

 

The arrow marks a centrilobular nodule that is coalescing with two similar nodules below it to form a macronodule. The dark blue center represents lumenal exudate.

The macronodules enlarge and merge to form the larger consolidations with irregular margins, which represent continuing endobronchial spread of disease.

 

High resolution CT may show a ground-glass appearance around consolidated regions corresponding to the pale bluish alveolitis adjacent to the consolidations [1].

Reference

1. Hatipoglu O, Osma E, Manisali M, Ucan E, Balci P, Akkoclu A, Akpinar O, et al. High resolution computed tomographic findings in pulmonary tuberculosis. Thorax 1996; 51:397-402.

Clinical summary Endobronchial tuberculosisDiscussion

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