Three cases of presumed pneumocystis pneumonia in patients receiving bortezomib therapy for multiple myeloma

• Three patients receiving bortezomib therapy for multiple myeloma presented with clinical and radiological features consistent with PCP.
• The patients deteriorated whilst receiving broad-spectrum antibiotics but responded to sulfamethoxazole + trimethoprim.
• The negative sputum PCR results in two patients may be due to the prior initiation of sulfamethoxazole + trimethoprim and absence of BAL specimens.
• The three patients were receiving dexamethasone at doses and durations at the threshold expected to cause PCP.
• 26S proteosome inhibitor therapy may be a risk factor for PCP and may necessitate concomitant PCP prophylaxis.

IntroductionThis paper presents three probable cases of pneumocystis pneumonia in patients receiving bortezomib therapy for multiple myeloma.Presentation of casesThree patients receiving bortezomib therapy for multiple myeloma presented with dyspnoea, non-productive cough, and fevers. These patients deteriorated despite receiving broad-spectrum antibiotic therapy with piperacillin + tazobactam and azithromycin and an assortment of other antimicrobials but promptly responded to sulfamethoxazole + trimethoprim therapy. Only one of the patients exhibited a positive Pneumocystis jirovecii PCR test but testing was sub-optimal.DiscussionAlthough only one of the patients exhibited a positive sputum P. jirovecii PCR test, the diagnosis of PCP in these three patients is supported by their; clinical and radiological features consistent with PCP, deterioration despite receiving broad-spectrum antibiotic therapy, and prompt responses to sulfamethoxazole + trimethoprim therapy. In the patients with negative P. jirovecii PCR bronchoalveolar lavage specimens were not obtained as these patients were deemed too high risk to undergo the procedure. Although the three patients were also receiving dexamethasone therapy, the doses and durations were at the threshold of those expected to cause PCP.Conclusion26S proteosome inhibitor therapy for multiple myeloma may be a risk factor for PCP and clinicians should adopt a high level of suspicion for PCP in patients receiving these medications until conclusive evidence is obtained.