A49-22 A Shocking Discovery: Pneumocystis as an Unlikely Cause of Pneumonia Leading to Septic Shock

Abstract Introduction Pneumocystis jirovecii pneumonia (PJP) is a rare but significant pulmonary infection in patients undergoing docetaxel chemotherapy for solid tumors. While the incidence of PJP among docetaxel-treated patients is low, ranging from 0.7% to 1% in large studies, the risk is heightened in individuals with severe CD4+ lymphopenia or additional immunosuppressive factors such as corticosteroid use. PJP represents a minority of pulmonary infections in these patients, with bacterial and other fungal pathogens being more common. Case reports have documented PJP in docetaxel-treated patients, even in those without prolonged corticosteroid therapy, suggesting multifactorial risks including chemotherapy-induced lymphocytopenia, prior chest irradiation, and intermittent steroid use. Clinical presentation is typically subacute, with fever, dyspnea, and diffuse pulmonary infiltrates, often associated with significant morbidity and mortality. Current guidelines do not recommend routine PJP prophylaxis or screening for all docetaxel-treated patients but advise consideration in those with additional risk factors like prolonged corticosteroid use or profound lymphopenia. Case Presentation A prostate cancer patient on docetaxel and low-dose prednisone presented with multifocal pneumonia, hypoxic respiratory failure, and septic shock. Initial workup excluded bacterial and viral pathogens, and chemotherapy-induced pneumonitis or community-acquired pneumonia were considered. Despite persistent respiratory failure and worsening symptoms, PJP was not initially suspected due to the absence of typical risk factors such as high-dose corticosteroid use, chest radiation, underlying pulmonary disease, or prolonged lymphopenia. However, bronchoscopy and bronchoalveolar lavage eventually confirmed PJP, and the patient improved with Bactrim therapy. Discussion This case highlights the diagnostic challenges of PJP in cancer patients. This case raises the question of whether PJP screening should be routine in cancer patients presenting with pneumonia. Current practice limits screening and prophylaxis to patients with additional risk factors for immunosuppression. Patients receiving docetaxel chemotherapy are at highest risk for PJP if they have severe lymphopenia, recent or concurrent high-dose corticosteroids (≥20 mg prednisone equivalent daily for ≥4 weeks), other immunosuppressive therapies, prior chest radiation, or underlying pulmonary disease. This patient did not meet these criteria for screening or prophylaxis, illustrating the complexity of diagnosing PJP in low-risk individuals. Vigilance and a multidisciplinary approach are essential in managing pneumonia in cancer patients, particularly when initial diagnostics do not reveal a clear etiology. This abstract is funded by: None