Pneumocystis pneumonia (PCP)

Case contributed by A.Prof Frank Gaillard

Presentation

Post chemotherapy for multiple myeloma.

Modality: X-ray

Bilateral hazy opacities predominantly in the midzones. 

Modality: CT

CT confirms widespread ground glass opacity, without pleural effusions. No pneumatocoeles. 

Lung biopsy isolated Pneumocystis jirovecii as well as CMV, however the changes seen were more in keeping with PCP than viral pneumonitis.

Histology

The wedge biopsies show acute lung injury. There is a mixture of organizing alveolar exudates, with more acute cellular/fibrinous exudates, including some hyaline membrane elaboration. The alveolar walls are mildly thickened with prominent type II pneumocytes.

Within the fibrinous exudates, a number of diagnostic clusters of pneumocystis organisms are identified on silver staining. In addition, rare cells show a dark burgundy-red inter-nuclear inclusion, consistent with cytomegalovirus. This is also confirmed by CMV immunohistochemistry. The immunohistochemistry for herpes simplex virus is negative.

The inflammatory pattern is probably best considered a type of organizing diffuse alveolar damage. The typical haemorrhagic, necrotising pneumonitis of CMV / HSV viral disease is not identified here, therefore, I suspect that the lung injury in this case is mostly due to pneumocystis

Case Discussion

This case illustrates the difficulty even with histology, in making a definitive diagnosis when multiple co-existing aetiologies are present. The need for multidisciplinary approach to care of such complicated cases is essential as each discipline in isolation struggles to put all the pieces together. 

This patient was treated with anti-PCP therapy and gradually improved. 

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Case Information

rID: 8545
Case created: 10th Feb 2010
Last edited: 15th Mar 2016
System: Chest
Inclusion in quiz mode: Included

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