Pediatrics International (2020) 62, 1121–1122

doi: 10.1111/ped.14315

Photos In Pediatrics

Magnetic resonance imaging diagnosis of acute focal bacterial nephritis with MERSGeorge Imataka,1 Shigeko Kuwashima2 and Shigemi Yoshihara1Yuji Fujita,1
1
Departments of Pediatrics, Dokkyo Medical University and 2Radiology, Dokkyo Medical University, Tochigi, Japan
Acute focal bacterial nephritis (AFBN) is a subtype of upper
urinary tract infection (UTI) with focal areas of non-liquefactive necrosis in the renal cortex. Most AFBN patients havepoor pyuria, often delaying the diagnosis of AFBN. Ultrasonography alone is insufficient to diagnose AFBN, as it isoften diagnosed by contrast-enhanced computed tomography(CT) that identifies a wedge-shaped kidney defect. However,clinicians are hesitant to perform contrast-enhanced CT
because of the risks associated with allergic reaction to thecontrast agents and radiation exposure.
Mild encephalitis/encephalopathy with a reversible spleniallesion (MERS) is an encephalopathy that presents with reversible splenial lesions of the corpus callosum upon magnetic
resonance imaging (MRI). Viral infections (such as influenzaor rotavirus) are commonly the cause of MERS and have
known to be complicated with Kawasaki disease1 and AFBN,
which is reported to be the possible cause of high C-reactive
protein in MERS patients.2 Although MERS prognosis isreportedly good,3 it is not always the case, as it can progress
to cerebellitis, resulting in neurological sequelae if associatedwith rotavirus infection.4 MERS with AFBN may also need tobe properly diagnosed and treated.
In our hospital, we diagnosed three patients with various
presentations of AFBN with MERS using diffusion-weighted
imaging (DWI) MRI of the brain and kidneys, as previously
described (Fig. 1).5 Patient 1, a 5-year-old boy, experienced
fever, headache, visual hallucinations, vomiting, and rightabdominal and back pain; his CRP level was 13.72 mg/dL.
Patient 2, a 3-year-old boy, presented with a fever, seizures,and visual hallucinations; his CRP level was 6.59 mg/dL.
Patient 3, a 3-year-old boy, experienced fever, uncharacteristic
behavior and speech, and vomiting; his CRP level was
7.68 mg/dL. Urine examinations for all patients showed nopyuria. Enterococcus faecalis was the identified bacterial
pathogen in all patients. None presented with neurologicalsequelae.
Informed consent for publishing this case report wasobtained from the patient’s parents.

Correspondence: Yuji Fujita, MD, Department of Pediatrics, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga
District, Tochigi 321-0293, Japan. Email: fujitay@dokkyomed.ac.jp
Received 20 March 2020; revised 23 April 2020; accepted 18May 2020.
© 2020 Japan Pediatric SocietyabcdefFig. 1

The usefulness of diffusion-weighted imaging (DWI) MRI
has been reported in acute pyelonephritis in adult patients,6and it may also be useful in AFBN. There is no requirement
for contrast agents and radiation exposure in MRI. In pediatricpatients, sedation is often required to perform MRI; however,each patient was diagnosed with AFBN and MERS simultaneously during the same sedation. Based on our experience,
MRI may be a good option for diagnosing AFBN, especiallywhen the patient presents with central nervous system symptoms indicative of MERS complications, such as convulsions,
impaired consciousness, and abnormal behavior.

1122 Y Fujita et al.

Acknowledgments
We wish to thank Editage (www.editage.com) for English language editing.

Disclosure
The authors declare o conflict of interest.

Author contributions
Y.F. drafted and revised the initial manuscript; G.I., S.K., andS.Y. critically revised the manuscript for important intellectualcontent. All authors read and approved the final manuscript.

References
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complicated by mild encephalopathy with a reversible spleniallesion (MERS). J. Neurol. Sci. 2012; 315: 167–9.

© 2020 Japan Pediatric Society

2 Maruyama Y, Sato M, Inaba Y et al. Comparison of mild
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