Pneumocystis Pneumonia Presenting as an Enlarging Solitary Pulmonary Nodule

Necrotizing Granulomatous Pneumocystis Infection Presenting as a Solitary Pulmonary Nodule: A Case Report and Review of the Literature

Pneumocystis jirovecii is an opportunistic fungus that is classically associated with pneumonia in immunocompromised patients, particularly those with human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS). However, this infection is now more commonly seen in those with malignancy, particularly lymphoproliferative disorders. Classic image findings with Pneumocystis jirovecii pneumonia (PJP) include bilateral ground-glass opacities with or without cyst formation. Up to 5% of patients with PJP may present with atypical image findings, specifically nodular opacities or masses thought to represent granulomatous inflammation. The differential diagnosis for a new solitary pulmonary nodule in an immunocompromised patient is broad. One must first rule out a recurrence of malignancy or new primary malignancy. In our patient's case, two nondiagnostic bronchoscopies with EBUS-TBNA eventually led to a surgical resection, which revealed a diagnosis of nodular necrotizing granulomatous Pneumocystis jirovecii. The diagnostic yield from EBUS is not well established, and most cases require surgical biopsy for definitive diagnosis. Further data regarding the use of EBUS-TBNA in diagnosing granulomatous PJP is needed.

Multiple Mass Lesions in Pneumocystis Pneumonia

We encountered a case of pneumocystis pneumonia (PCP) presenting with multiple mass lesions in a human immunodeficiency virus (HIV)-negative patient. Diagnosis of PCP before bronchoscopy was difficult because chest computed tomography (CT) findings were atypical of PCP and a serum (1,3)-β-D-glucan concentration was within normal limits. Bronchoscopic biopsy and Grocott’s staining enabled the diagnosis of PCP. PCP can show various patterns on chest CT images, depending on the immune status of the host. In high-risk patients, such as those who are immunocompromised, bronchoscopy should be performed with suspected cases of PCP, even if CT imaging does not show typical ground-glass opacity.