Introduction
Opsoclonus myoclonus syndrome (OMS) is a rare paraneoplastic syndrome associated with neuroblastoma (NB) in 50-80% cases. The aim of the study was to analyze characteristics of neuroblastoma associated with OMS treated in the multicenter study in Russia.
Methods
285 patients with sympathetic nervous system tumors were included for the period 01.2012-06.2015 (42 months). 19 (6.7%) patients had tumor associated with OMS. The diagnosis has been established on the basis of international criteria of OMS. The diagnosis of NB has been confirmed by histological examination in all cases. Patients were stratified and treated according to the German NB2004 protocol.
Results
Male: female ratio was - 0.35:1. The median age at the diagnosis of OMS and NB was 24.7 months (range 14.9-54.0). Paravertebral location was noted in 15/19 (78.9%) cases. Most tumors were small (median volume - 6.5 ml (range 0.4-80.9 ml). In 11/19 (58.0%) patients the tumor was visualized only by CT/MRI. Increased neuron specific enolase was observed in 1/19 (5.3%) case. Scintigraphy with metaiodobenzylguanidine (MIBG) was positive in only 9/17 (53.0%) cases. Segmental aberrations were observed in 1 patient (11q deletion). All but 1 patient were stratified to the observation group. Comparing with non-OMS cases NB associated with OMS showed female preponderance (p=0.005), older age at tumor diagnosis (24.7 versus 11.2 months, p=0.02), non-adrenal primary tumor (p=0.0008), more differentiated histology (p=0.0001), lack of MYCN amplification (p=0.057) and 1p deletion (p=0.04), favorable stage (p=0.003) and risk group distribution (p=0.003). 3-year EFS was 82.6% in OMS group and 61.6% in non-OMS group (p=0.22), 3-year OS - 100.0% and 72.7% (p=0.2).
Conclusion
NB associated with OMS showed more favorable biologic characteristics. CT and/or MRI are the most informative diagnostic methods to detect tumors in patients with OMS given the small size, location and low metabolic activity of NB.