A case of invasive pulmonary aspergillosis associated with clozapine-induced agranulocytosis

Background: Clozapine-induced agranulocytosis (CLIA) is a rare but serious complication. Fever associated with CLIA is typically treated with broad-spectrum antimicrobials, but empiric antifungal therapy is rarely used. While bacterial and viral infections have been reported in CLIA cases, no cases of fungal infections complicated by CLIA have been documented. We report the first case of CLIA complicated by invasive pulmonary aspergillosis (IPA) in a patient with schizophrenia. The diagnosis of IPA was made using serum beta-D-glucan, Aspergillus galactomannan antigen tests, and chest computed tomography (CT).
Case presentation: We present a case of a 51-year-old man with schizophrenia who developed CLIA complicated by IPA. The patient, diagnosed with treatment-resistant schizophrenia, was started on clozapine, but 9 months later he presented with fever, cough, leukopenia, and neutropenia. Clozapine was discontinued, and empirical treatments with cefepime and filgrastim were initiated. Serum beta-D-glucan and Aspergillus galactomannan antigen tests were positive, and chest CT showed well-circumscribed nodules, leading to a probable diagnosis of IPA. Antifungal therapy was switched from micafungin to voriconazole according to guidelines. His neutropenia and fever improved, and he was re-transferred to a psychiatric hospital.
Conclusion: CLIA can be complicated by fungal infections. When patients with CLIA present with fever, fungal infections, including IPA, should be considered in the differential diagnosis. Serological tests, including beta-D-glucan and Aspergillus galactomannan, are useful for the diagnosis of IPA as well as the appropriate use of antifungal agents in patients with CLIA.