Respiratory bronchiolitis interstitial lung disease

Case contributed by Frank Gaillard
Diagnosis certain

Chest radiograph

x-ray

Patchy bilateral lung opacities with a mid-upper zone distribution. 

2 mth after initial CXR

ct

INDICATION: HIV positive, groundglass infiltrate, ? improvement post Septra treatment.

FINDINGS: Minor deterioration in the ground glass infiltrate is noted in the posterior aspect of the right upper lobe and in the posterior aspect of the right lower lobe. The remaining areas of ground glass show no interim change. The focal area of rounded pneumonia in the left lower lobe has almost completely resolved in the interim. The small focal area of consolidation in the posterior basal segment right lower lobe is unchanged in appearance in the interim.

Multiple bullae persist predominantly in an upper and mid lung zone distribution. Multiple small shotty lymph nodes also remain in the abdomen and in the mediastinum.

No pleural effusion.

Impression

Appearances are still strongly consistent with a PCP. However, given the absence of significant change on Septra, other considerations should also be considered. These would include viral infection, and non-infectious etiologies like RB-ILD and EAA could also give this appearance.

6 mth after initial CXR

x-ray

The lungs and pleural spaces are clear. 

8 mth after initial CXR

ct

The previously described extensive patchy bilateral ground-glass opacities are less dense and less conspicuous, but persist. Mild centrilobular emphysema is again noted, predominantly in the upper lobes. Mild air trapping is again identified at the lung bases, in keeping with small airways disease.

The 1.1 cm spiculated nodule in the posterior basal segment of the right lower lobe is unchanged. No new lung nodules or focal areas of lung parenchymal consolidation. A surgical staple line is seen at the posterior aspect of the right major fissure and lateral aspect of the superior segment of the right lower lobe, related to the previous open lung biopsy.

Case Discussion

Bronchial washings and biopsy negative.

Final Diagnosis: Wedge biopsy, RLL: histological features of respiratory bronchiolitis; special stains negative for PCP

Final Diagnosis Comment:  Sections from both the right upper and lower lobes show clusters of finely pigmented alveolar macrophages (smoker's macrophages) in centrilobular aggregates as well as dispersed in the more distal lobular alveoli. Attending this is evidence of centrilobular emphysema and some mild small airway thickening with occasional bronchioles harboring a lymphocytic infiltrate that could be called minimal intensity. There is no evidence of parenchymal fibrosis. Morphologically, this is respiratory bronchiolitis.

PCP stains are negative. There is no evidence of a granulomatous reaction or any proteinaceous alveolar exudate. 

The clinical and radiological correlation suggests RB-ILD. Typically the pathology in such cases is generally depicted as demonstrating more diffuse changes than is noted in this biopsy but I suspect that we are seeing a variability of sampling.

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