A Case of Steroid-Responsive Severe Pneumonia Following a Recent COVID-19 Infection in a Patient With Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infection.

A twenty-two-year-old woman with a history of pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) on rituximab presented with fever, abdominal pain, and worsening shortness of breath requiring supplemental oxygen via nasal cannula one month after a severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection from which she was minimally symptomatic and had recovered. Radiographic studies revealed bilateral patchy consolidations interspersed with ground-glass opacities (GGO). She was started on antibiotics for presumed community-acquired pneumonia with no improvement. Echocardiography revealed preserved biventricular function and a suspected intracardiac mass. A cardiac magnetic resonance imaging (CMRI) revealed myocarditis and no intracardiac mass. Fever persisted and oxygen requirements increased from FiO2 0.4 to 1.0. Repeat CXR showed subtotal left hemithorax opacification. Bronchoscopic samples showed a negative Gram stain and an unremarkable cell count differential. In view of this and given her lack of response to antibiotics with worsening respiratory status, high-dose steroids were started. She improved rapidly, and six days later she was off oxygen. Transbronchial biopsies showed benign parenchyma with some intra-alveolar fibrin deposition with no definitive evidence of viral cytopathic effect, vasculitis, or diffuse alveolar damage (DAD). Follow-up imaging in the pulmonary clinic revealed improvement of prior airspace disease with some new migratory opacities that completely resolved after 12 weeks. Pulmonary function tests and repeat CMRI were normal three months after discharge. Multisystem inflammatory syndrome in adults (MISA), post-covid organizing pneumonia (OP), and immune reconstitution inflammatory syndrome (IRIS) are rare and potentially steroid-responsive causes of pneumonia, which were in our differential diagnosis. It is imperative to consider the rare possibility of steroid-responsive pneumonia-like MISA, post-COVID-OP, and IRIS in patients with worsening respiratory symptoms following a recent SARS-CoV 2 infection.