A 6-year-old boy was hospitalized at Haiphong Children Hospital because of phlegmon behind his right ear and high fiver (40 C). Physical examination exhibited consciousness, pale skin, cutaneous abscess behind right ear, pustulosis on skin, foot fungus, and mouth ulcer (Figure 1A,C,D). Laboratory studies revealed severe neutropenia (white blood cells, 6.9 x 109/L; neutrophils, 0.2 x 109/L; lymphocytes, 2.67 x 109/L; monocytes, 3.38 x 109/L). A gram-stain and culture of abscess fluid showed S. aureus, which was susceptible to vacomycin and amikacin. Bone marrow aspirate exhibited normal myeloid cells, reduced granulocyte cell line, but no malignant cells. Serum titers of IgG, IgM, IgA and IgE and percentage of CD4+, CD8+ T cells were normal. Tests of HIV, HBV, HCV, EBV, and CMV were negative. The patient was treated with antibiotics according to antimicrobial susceptibility testing, abscess incision and drainage, and G-CSF. Two weeks later, the patient was discharged from hospital.
Because of severe neutropenia and infection, we carefully asked medical history and analysed medical records of the patient. From 8 months of age, the patient had recurrent infections, Staphylococcal pneumonia and Staphylococcal septicemia at 10 and 15 moths of age, respectively. In addition, he had cutaneous abscesses and other respiratory infections frequently. Because his infection status was not fully recovered by using antibiotics, from 23 to 30 months of age, the patient was treated with antituberculosis drugs although there was not any evidence of mycobacterium tuberculosis. At the 41 months of age, the patient had necrotizing pneumonia due to S. aureus leading right parietal lobectomy (Figure 1B). At that time, he was diagnosed with autoimmune neutropenia in infancy (AIN) although anti-neutrophil antibodies were not performed. After using solumedrol, neutropenia and infection statuses got worse. Moreover, patient had severe neutropenia in many times (Table 1).
Considering his medical history, current clinical signs, and laboratory findings, SCN associated with ELANE abnormality was suspected. Direct DNA sequencing analysis demonstrated a heterozygous missense mutation of the 242th base (G to C) in exon 3, resulting change of the 81 codon (Arginine to Proline), which has been reported to cause severe neutropenia (R81P) (Figure 2).