Abstract
We report three children who developed Pneumocystis pneumonia (PCP) during maintenance chemotherapy for acute lymphoblastic leukemia. We could not identify Pneumocystis jiroveci in biological specimens, but PCP was diagnosed on the basis of rapidly progressive hypoxemia, chest radiographic findings, elevated serum levels of (1→ 3) β-D-glucan, differential diagnosis from other infectious diseases, and the patients' clinical courses. Elevated levels of serum ferritin, soluble interleukin-2 receptor, and urinary β2 microglobulin were revealed, and apparent hemophagocytosis was seen in bone marrow smears from one patient who underwent bone marrow aspiration. Adjunctive corticosteroids with TMP-SMX were effective, and the delay in starting corticosteroid treatment led to worsening of the respiratory conditions as well as laboratory and radiographic findings. Adjunctive corticosteroids were considered to be effective for the host inflammatory response to Pneumocystis jiroveci which affected the clinical condition of these patients. These laboratory findings, suggesting the presence of hypercytokinemia, might be useful markers for deciding the use of adjunctive corticosteroids for PCP.
