| Increased brain (megalencephaly) | | Anatomic | | Familial megalencephaly | | Neurocutaneous disorders (eg, neurofibromatosis, tuberous sclerosis, linear sebaceous nevus syndrome, Sturge-Weber syndrome, Klippel-Trenaunay-Weber syndrome, basal cell nevus syndrome syndrome]) | | Autism spectrum disorder | | Achondroplasia | | Cerebral gigantism (Sotos syndrome) | | Fragile X syndrome | | PTEN hamartoma syndromes (eg, Cowden/Bannayan-Riley-Ruvalcaba syndrome) | | Metabolic | | Leukodystrophies (eg, Alexander disease, Canavan disease, megalencephalic leukoencephalopathy) | | Lysosomal diseases (eg, Tay-Sachs, mucopolysaccharidosis, gangliosidosis) | | Organic acid disorders (eg, glutaric aciduria) | | Increased cerebrospinal fluid | | Hydrocephalus* | | Benign enlargement of the subarachnoid space | | Hydranencephaly | | Choroid plexus papilloma | | | Increased blood | | Hemorrhage (intraventricular, subdural, epidural, subarachnoid) | | Arteriovenous malformation | | Increased bone | | Bone marrow expansion (eg, thalassemia major) | | Primary bone disorders (eg, skeletal and cranial dysplasias such as achondroplasia, osteogenesis imperfecta, cleidocranial dysostosis, metaphyseal dysplasia, osteopetrosis, hyperphosphatasia) | | Increased intracranial pressure | | Idiopathic (pseudotumor cerebri) | | Infection or inflammation (eg, meningitis) | | Toxins (eg, lead) | | Metabolic abnormalities (eg, vitamin A deficiency or excess, galactosemia) | | Mass lesions | | Intracranial cyst | | Intracranial tumor | | Intracranial abscess | |
