Pneumocystis jirovecii pneumonia presenting as a large pulmonary mass in a patient with AIDS

Pneumocystis jirovecii pneumonia typically presents with diffuse bilateral infiltrates or ground-glass opacities. However, the radiographic pattern may be atypical. We report a case of a woman in her 40s who presented with multiple pulmonary masses and prolonged symptoms of non-productive cough, generalised weakness and fatigue. Serial chest CT performed prior to her presentation showed a large right lower lobe lung mass with multiple additional bilateral pulmonary nodules. Her workup revealed a new diagnosis of AIDS. Pathology of several CT-guided needle biopsies was consistent with Pneumocystis which was confirmed by microbial DNA sequencing. No additional pathogens were identified. Her clinical symptoms and radiographs improved significantly with trimethoprim-sulfamethoxazole and treatment of her HIV infection. Clinicians should evaluate for underlying immunodeficiency and seek infectious disease and pulmonary consultation early for consideration of alternative diagnoses when patients present with cough, dyspnoea and atypical chest radiographs, and initial pathological examination is unrevealing.