Pneumocystis jirovecii pneumonia as an initial manifestation of hyper-IgM syndrome in an infant: A case report

Kim, Danbi; Shin, Ju Ae; Han, Seung Beom; Chung, Nack-Gyun; Jeong, Dae Chul

A lymphocyte subset test was performed on HD #3, and revealed the following results: CD3+ cells, 37.3%; CD4+ cells, 22.9%; CD8+ cells, 13.1%; CD19+ cells, 61.7%; and CD56+ cells, 0.6%. IgG (557 mg/dL) and IgM (74 mg/dL) levels were within normal limits; however, IgA and IgE levels could not be measured. Immunoglobulin levels measured 1 month after admission showed similar results. Genetic studies for HIGM syndrome were requested based on the repeated results of the immunologic tests. One month after discharge, a novel frameshift mutation on exon 1 of the CD40 ligand (CD40L) gene was identified using gene sequencing. The identical mutation was identified in his mother as a heterozygote, and the patient was eventually diagnosed with X-linked HIGM syndrome. TMP/ SMX prophylaxis and intravenous immunoglobulin replacement therapy every 3 weeks was continued. He underwent unrelated, matched peripheral blood stem cell transplantation 8 months after the diagnosis of PCP, and 20 months have passed after transplantation without severe complications.