Transient gallium uptake in the ilium of an 11-year-old Japanese girl with anti-NMDA receptor encephalitis: a case report

Introduction Anti- N -methyl- d -aspartate receptor encephalitis often present with atypical psychiatric or non-specific behavioral symptoms in children, making early diagnosis challenging. We report a pediatric case in which gallium scintigraphy showed a transient, incidental uptake. Case report An 11-year-old girl developed subacute behavioral changes, memory impairment, abnormal movements, autonomic symptoms, and impaired consciousness. A cerebrospinal fluid analysis revealed the presence of oligoclonal bands and anti-NMDA receptor antibodies. Brain MRI showed focal abnormalities in the left frontal white matter, and 123 I-iomazenil single-photon emission computed tomography (SPECT) demonstrated mildly decreased uptake in the left frontotemporal region. 67 Ga SPECT/CT revealed transient gallium uptake in the left ilium, without evidence of a tumor. The patient received repeated courses of high-dose intravenous methylprednisolone and immunoglobulin, resulting in gradual neurological and psychiatric improvement. Her activities of daily living returned to baseline after one year, and follow-up gallium scintigraphy revealed resolution of the abnormal uptake. Discussion The transient gallium uptake was interpreted as a nonspecific, incidental finding without diagnostic or therapeutic implications. Although gallium scintigraphy can detect inflammatory or lymphoid lesions in other conditions, its clinical utility in anti-NMDAR encephalitis remains unestablished, and the present case does not support its use for evaluating paraneoplastic processes. In this case, early immunotherapy was associated with gradual neurological recovery.