Diagnostic value of whole-body MRI in Opsoclonus-myoclonus syndrome: a clinical case series (3 case reports)

BACKGROUND: Opsoclonus-myoclonus syndrome (OMS) is a rare clinical disorder and typically occurs in association with occult neuroblastic tumor in pediatric patients. I-123 metaiodobenzylguanidine (mIBG) scintigraphy is widely adopted as screening procedure in patients with suspected neuroblastic tumor. Also, contrast-enhanced magnetic resonance imaging (MRI) or computed tomography (CT) are involved in the imaging workup, primarily for the assessment of the primary tumor region. However, the diagnostic value of whole-body MRI (WB-MRI) for the detection of occult neuroblastic tumor in pediatric patients presenting with OMS remains unknown. CASE PRESENTATION: We present three cases of patients with OMS, in whom WB-MRI revealed occult neuroblastic tumor masses, whereas scintigraphy was inconclusive: In a 17 months old girl with OMS, WB-MRI revealed a paravertebral mass. After thoracoscopic resection, histopathology revealed a ganglioneuroblastoma. A 13 months old boy presenting with OMS WB-MRI detected a tumor of the left adrenal gland; histopathology demonstrated a ganglioneuroblastoma after adrenalectomy. In a 2 year old boy with OMS, immunoscintigraphy at the time of diagnosis was inconclusive. At the age of 13 years, a WB-MRI was performed due to persistent neurological symptoms, revealing a paravertebral retroperitoneal mass, which was classified as ganglioneuroblastoma. CONCLUSION: In OMS, particularly in the setting of inconclusive scintigraphy, WB-MRI may be considered as a valuable alternative in the early phase of diagnostic work-up.