A 21 month-old boy was admitted to the Neurodevelopmental Center because of failure to thrive, which began at the age of six months and was initially diagnosed as food allergy. Physical examination revealed emaciation (weight <3rd percentile), normal body length, normal head circumference with a characteristic “pseudohydrocephalic” face (fig. 1), as well as a mild pyramidal tract dysfunction (increased tendon reflexes, positive Babinski’s and Rosollimo’s signs, ankle clonus and a mild convergent squint bilaterally), in an otherwise alert child with appropriate cognitive abilities for his age. The performed MRI of the brain disclosed the underlying diagnosis (fig. 2).