Refractory mediastinal pyogenic lymphadenitis in a patient with chronic mucocutaneous candidiasis.

Chronic mucocutaneous candidiasis disease (CMCD) is an inborn error of immunity characterized by persistent and recurrent mucosal infections caused by Candida spp. STAT1 gain-of-function (GOF) is the main causative gene of CMCD and confers resistance to several pathogens including opportunistic ones, such as Candida spp. This report describes the case of a four-year-old boy with CMCD due to STAT1 GOF variant complicated by refractory mediastinal pyogenic lymphadenitis. The patient received seven weeks of intravenous therapy and subsequently four weeks of oral antibiotics and was cured with no relapse after completion of therapy. During antibiotic therapy, the patient developed exudative pleural effusion and required thoracentesis to improve respiratory distress. Despite the negative culture test results, the patient responded well to antibiotics and was suspected of having a bacterial infection. The immunodeficiency spectrum of CMCD suggested that the infection might have been caused by Staphylococci or Streptococci. In this patient, finding optimal secondary prophylaxis against bacteria was challenging because of allergic reactions to trimethoprim/sulfamethoxazole and subcutaneous immunoglobulin and drug interactions between azole and macrolide antimicrobial agents. Although Janus kinase inhibitors and allogeneic hematopoietic cell transplantation are options, neither treatment is supported by reliable evidence. Further studies are needed to understand the bacterial infections that occur in patients with CMCD and develop better prophylactic management against microorganisms.