Diencephalic syndrome in childhood, a challenging cause of failure to thrive: miniseries and literature review

The aim of our study was to better define the clinical pattern of diencephalic syndrome, a rare but potentially lethal cause of failure to thrive in infancy. Poor weight gain or weight loss, the characteristic presenting feature, often firstly attributed to gastrointestinal or endocrinological or genetic diseases, is secondary to a malfunctioning hypothalamus, caused by a diencephalic tumor. Due to its unexpected clinical onset, diagnostic delay and misdiagnosis are common. We described a case series of 3 children with diencephalic syndrome admitted at our Hospital, over a 5-year period. Furthermore, a narrative review on all pediatric cases published in the last seventy years was performed. Clinical pattern, timing to diagnosis, neuroimaging, management, and outcome were analyzed. Our three cases are singularly described in all clinical and diagnostic findings. Overall, 100 children were selected; all these cases as well as our children presented with failure to thrive: 96% had body mass index or weight-length/height ratio lower than 5^th percentile. Vomiting and hyperactivity are reported in 35 and 26% of cases, respectively. The neurological features, mainly nystagmus reported in 43%, may occur late in the disease course. In conclusion, the diagnostic delay is the hallmark of diencephalic syndrome, confirming the lack of knowledge by clinicians. The poor weight gain/loss despite adequate length growth and food intake, especially in children with hyperactivity and good psychomotor development, should alert pediatricians towards this condition, before neurological signs/symptoms occurrence.