Expanding the differential: Goodpasture's disease in the setting of the COVID-19 pandemic

Introduction: The 2020 COVID-19 pandemic was a challenging time in healthcare. Physicians struggled with limited resources, overwhelming patient volume and limited knowledge of COVID-19. During this period many hypoxemic patients with pulmonary infiltrates were empirically managed as COVID-19 patients. However, anchoring to COVID-19 diagnosis narrows differentials and potentially lead to missed diagnosis. Herein we highlight a case of delayed Goodpasture's disease diagnosis in the setting of COVID-19 pandemic. Case Description: A 51 year old male was admitted for several days of malaise, diarrhea and decreased oral intake. On arrival the patient was hypothermic 88.6 oF, BP 122/67 mm Hg, SpO2 91% on room air. On exam he was encephalopathic, diffusely edematous with sonorous wheezes. Initial labs notable for (mEq/L): Na 135, K 7, Cl 107, low CO2 8, significantly elevated BUN 184 and Cr 27.9. CT chest showed bilateral airspace opacities, renal ultrasound was unremarkable. Initial diagnosis was sepsis secondary to presumed COVID-19 infection despite several negative COVID tests. Emergent hemodialysis was complicated by hypotension and hypoxemia requiring intubation. The patient rapidly deteriorated requiring 3 vasopressors. Autoimmune serologies resulted several days later were negative (ANA, ANCA, C3, Anti-dsDNA Ab, Hepatitis B/C, HIV, SPEP with immunofixation) with the exception of positive anti-GBM IgG Ab (>8). Renal biopsy was unattainable given his tenuous clinical status;however, bronchoscopy performed revealed bloody aliquots consistent with alveolar hemorrhage. The patient was subsequently started on cyclophosphamide, pulse dose steroids and plasmapheresis. Respiratory status steadily improved allowing ventilator liberation. The patient underwent several more cycles of immunosuppression, plasmapheresis during hospitalization and was discharged after 80 days. 1 year later the patient remains dialysisdependent. Discussion: This case illustrates the unique challenges of diagnosing Goodpasture's Disease (GD), a rare immune complex-mediated small vessel vasculitis characterized by alveolar hemorrhage and renal insufficiency, during the COVID-19 pandemic. Similarities in their presentation (pulmonary infiltrates, hypoxemia, renal failure) led to our patient being initially treated for COVID-19. However, maintaining a broad differential is essential as the treatment for GD and COVID-19 are vastly different.