Challenges towards management of CARD9‐deficient patients with phaeohyphomycosis: A case report and case series study

A number of recalcitrant phaeohyphomycosis cases with a life-threatening prognosis have been observed in CARD9-deficient patients, but little is known about the long-term management strategies that are effective for such intractable individuals.To study the genetic and immunological mechanisms underlying recalcitrant phaeohyphomycosis and to share our clinical experiences regarding its treatment.Ten CARD9-deficient patients with recalcitrant phaeohyphomycosis admitted to our centre in the past two decades were followed-up, and their clinical presentations, laboratory findings, treatment and prognoses were analysed; one of them was a novel case of recalcitrant phaeohyphomycosis harbouring CARD9 mutations. Innate and adaptive immunological responses of patient-derived peripheral blood mononuclear cells were evaluated using ELISA and flow cytometry.We identified a total of seven CARD9 mutations in the ten analysed patients. Moreover, patient-derived cells exhibited a significant impairment of innate and adaptive immune responses upon fungus-specific stimulation. All the patients experienced recurrence and exacerbation; four of them died, two exhibited continued disease progress with unsatisfactory therapeutic efficacy, three showed obvious improvement under maintenance therapy, and only one achieved a clinical cure.Our study highlighted that otherwise healthy patients diagnosed with early-onset, unexplained and recalcitrant phaeohyphomycosis should be analysed for CARD9 mutations and immune deficiency. Thereafter, the length and choice of management remain challengeable and must be adjusted based on the clinical presentations and responses of patients over their lifetimes. Although continued posaconazole treatment may be the promising first-line therapy at present, novel strategies are worth exploring.