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Shiga toxin-producing Escherichia coli (STEC) is a consequential foodborne pathogen worldwide. The most prevalent STEC O serogroups--O157, O26, O111, O103, O121, O145, and O45--cause severe symptoms, including bloody diarrhea and [...]

Background Rituximab, an anti-CD20 antibody that targets B cells, is a promising agent against steroid-dependent and steroid-resistant nephrotic syndrome in children. Case-Diagnosis/Treatment We report a 3-year-old boy who presented with atypical Pneumocystis jiroveci pneumonia (PCP) following administration of rituximab for refractory nephrotic syndrome. He had received cyclosporine and daily prednisolone for over 1 year. Following rituximab therapy, a hazy shadow was observed on his chest X-ray. Chest-computed tomography revealed multiple nodular lesions in bilateral lungs, although his clinical symptoms were subtle. PCR analysis demonstrated the presence of Pneumocystis DNA in his bronchoalveolar lavage. Lung wedge resection of the nodular lesion exhibited granulomas containing a few cysts of P. jiroveci that primarily consisted of T cells and histiocytes and lacked B cells. A deficiency of B cells following rituximab treatment suggests a dramatic effect on the immune response and, therefore, could result in granulomatous PCP. Nodular granulomatous lesions of PCP comprise an emerging concept previously reported in adults with hematological disease, bone marrow transplant, or treatment with rituximab. We report the first pediatric case of nodular PCP. Granulomatous PCP can be life-threatening. Moreover, bronchoalveolar lavage often fails to demonstrate the presence of P. jiroveci DNA. Wedge biopsy is warranted for definitive diagnosis. Our patient fully recovered with sulfamethoxazole/trimethoprim treatment because of early detection. Conclusions The indication of rituximab for refractory nephrotic syndrome has increased recently. Therefore, recognition of the risk of atypical PCP is important. Our findings suggest that PCP prophylaxis should be considered following rituximab therapy. Keywords Nephrotic syndrome * Rituximab * Pneumocystis jiroveci * Granulomatous * Granulomatous Pneumocystis jiroveci pneumonia, Abbreviations PCP Pneumocystis jiroveci pneumonia RTX Rituximab NS Nephrotic syndrome FRNS Frequently relapsing nephrotic syndrome SDNS Steroid-dependent nephrotic syndrome SRNS Steroid-resistant nephrotic syndrome Introduction Treatment of refractory childhood nephrotic syndromes, [...]