Necrotizing Mediastinal Mass and Cavitary Pneumonia From Probable Co-infection With Epstein-Barr Virus and Mycoplasma pneumoniae.

Mycoplasma pneumoniae (MP) is a bacterium commonly known to cause mild respiratory infections, especially in young children. Epstein-Barr virus (EBV) is a herpesvirus that causes infectious mononucleosis, typically a mild illness in younger individuals. However, in its severe form, EBV can cause pneumonia. Severe pneumonia resulting from co-infection with MP and EBV is rare, with few cases reported in the literature, mostly in the pediatric population. We report a case of a 20-year-old man who presented with a one-week history of progressively worsening right-sided pleuritic chest pain, subjective fevers and chills, night sweats, and a productive cough with purulent sputum. An initial extensive infectious work-up was unremarkable. Computed tomography (CT) imaging of the chest revealed a heterogeneous, possibly necrotic, posterior mediastinal mass, part of which encased the right inferior pulmonary vein and cavitary pneumonia. A previous CT scan of the abdomen, which captured the lower mediastinum three weeks prior to presentation, did not show the presence of this mass, suggesting a bacterial origin. There was no response to initial empiric antimicrobials, necessitating an escalation of the antimicrobial regimen. After extensive work-up, the patient was found to have positive Mycoplasma immunoglobulin M (IgM) and positive EBV; however, Mycoplasma PCR testing could not be obtained. The antibiotic regimen was modified to include azithromycin, resulting in marked clinical improvement. Repeat CT scans at two weeks and three months showed a reduction in the size of the necrotic mass. The patient was subsequently discharged home in stable condition and has remained well.