Hypothalamic hamartoma true true true Hamartoma human_phenotype HP:0002444 UMLS:C0342418 SNOMEDCT_US:237714006 MSH:C537158 Hypothalamic hamartoma is a malformation, not a tumor. Hypothalamic hamartomas grow at the rate of, or slower than, the surrounding brain tissue. A hamartoma of the hypothalamus appears as a non-enhancing mass in the floor of the third ventricle posterior to the optic chiasm that is isointense to grey matter on T1 and T2 pulse sequences of an MRI, but may have distinct intensity on FLAIR (neither cranial CT examination nor cranial ultrasound examination is adequate for diagnosis of hypothalamic hamartom). Individuals with hypothalamic hamartomas may have neurologic symptoms, although most are asymptomatic. Removal of the hypothalamic hamartoma is not indicated and often results in iatrogenic pituitary insufficiency. http://www.case.edu/EpSO.owl#Hamartoma The presence of a hamartoma of the hypothalamus. http://www.case.edu/EpSO.owl#HypothalamicHamartoma Hypothalamic hamartomas are rare malformations of fetal brain development, affecting development of the hypothalamus, and are placed within the spectrum of grey matter heterotopia. Pathologically, lesions show mature neuronal and glial cells and some myelinated fibres. Malformations of Cortical Development