Hypothalamus Lesion
Anne G. Osborn, MD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Pilocytic Astrocytoma
Diffuse Astrocytoma, Low Grade
Less Common
Craniopharyngioma
Germinoma
Neurosarcoid
Langerhans Cell Histiocytosis
Lipoma
Lymphocytic Hypophysitis
Metastases
Hypothalamic/Pituitary Axis Metastases
Lymphoma
Leukemia
Tuber Cinereum Hamartoma
Ectopic Posterior Pituitary
Rare but Important
Other Gliomas
Chordoid Glioma
Pilomyxoid Astrocytoma
Pituicytoma
Ganglioglioma
Demyelinating Disease
Multiple Sclerosis
ADEM
Wernicke Encephalopathy
Cavernous Malformation
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Anatomic essentials
Hypothalamus lies below level of anterior, posterior commissures
Inferior hypothalamus formed by
Anterior recesses of 3rd ventricle
Tuber cinereum
Mamillary bodies
Infundibular stalk
Differentiating features of hypothalamic lesions based on
Precise anatomic sublocation (e.g., infundibulum)
Patient age
Clinical presentation
CT/MR features (density/signal intensity, enhancement, Ca++)
Helpful Clues for Common Diagnoses
Astrocytoma
Most common primary neoplasm of hypothalamic-optic chiasm region
Usually low grade (pilocytic > WHO grade II fibrillary)
Age < 5 years
Endocrine dysfunction in 20%
Look for evidence for NF1
20-50% of patients with pilocytic astrocytoma
Helpful Clues for Less Common Diagnoses
Craniopharyngioma
Second-most common suprasellar mass in children
Occurs anywhere from intrasellar to stalk to anteroinferior 3rd ventricle
90% calcify, 90% have multiple cysts (mixed signal intensity), 90% calcify
Germinoma
Can be primary in hypothalamus/stalk
M = F (vs. male predominance in pineal gland)
10% “double” midline lesions (pineal & hypothalamus)
DI, diencephalic syndrome, precocious puberty common
Thick enhancing stalk, 3rd floor, absent posterior pituitary “bright spot”
Neurosarcoid
Adult with stalk, meningeal lesions
Other infectious/inflammatory lesions that can mimic sarcoid
Wegener granulomatosis
TB, syphilis
Langerhans Cell Histiocytosis
Stalk/hypothalamus lesion in a child
Lipoma
Lipoma: Sessile T1 hyperintense lesion on subpial surface of hypothalamus
Osteolipoma: Rare; fat density/signal intensity & calcification
Lymphocytic Hypophysitis
Peripartum female most common
Can mimic macroadenoma
Metastases
Hypothalamic/Pituitary Axis Metastases
1-25% of systemic cancers at autopsy
Less common at imaging
Breast, lung most common primary tumors
Lymphoma
Pituitary/stalk/hypothalamus uncommon site
Can be primary or metastatic
Leukemia
Often involves dura, paranasal sinuses
Tuber Cinereum Hamartoma
Children with gelastic seizures, males with isosexual precocious puberty
Can be pedunculated or sessile
Density/signal intensity typically isointense with cortex
No Ca++, enhancement
Sessile lesion may be difficult to distinguish from hypothalamic astrocytoma (no change on follow-up)
Helpful Clues for Rare Diagnoses
Other Gliomas
Chordoid Glioma
Floor of 3rd ventricle
Hyperintense with strong, uniform enhancement
Pilomyxoid Astrocytoma
Infant/young child
“H”-shaped tumor of hypothalamus; extension into medial temporal lobes common
Often large, bulky, ± hemorrhage (rare in pilocytic astrocytoma)
± Hemorrhage (25% of PMAs; rare in pilocytic astrocytoma)
Pituicytoma
Stalk, posterior pituitary lobe
Low grade astrocytoma
Enhances strongly, uniformly
Ganglioglioma
Very rare in hypothalamus/chiasm
Young adult (mean age = 20 years)
Demyelinating Disease
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