CMV disease complicating induction immunosuppressive treatment for ANCA-associated vasculitis

We present a case of a 71-year-old woman who initially presented with renal-limited antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Following standard therapy with cyclophosphamide, steroids and plasma exchange, her renal function began to improve. However, despite appropriate treatment, her renal function subsequently deteriorated and she suffered haemoptysis. Owing to diagnostic uncertainty, bronchoscopy and a repeat renal biopsy were performed. The bronchoscopy washings demonstrated positivity for cytomegalovirus (CMV) DNA, and in combination with a positive serum CMV PCR, immunosuppression was withheld. Treatment with ganciclovir was started. Repeat renal biopsy demonstrated active vasculitis and, following successful treatment of CMV disease, immunosuppression was re-started alongside prophylactic valganciclovir. This resulted in a successful outcome for the patient. Pulmonary CMV disease may mimic pulmonary disease associated with vasculitis, posing a diagnostic challenge to clinicians. We recommend a low threshold when testing for CMV in these patients.