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KEY FACTS

Terminology
- a.k.a. tuber cinereum hamartoma
- Nonneoplastic; congenital gray matter heterotopia
Imaging
- Hypothalamic mass contiguous with tuber cinereum - Located between mammillary bodies and infundibulum - Can be sessile or pedunculated ("collar button") - Size ranges from few mm to several cm
- Isointense with gray matter on T1WI - Can be slightly hyperintense on T2/FLAIR - Large lesions can be heterogeneous, contain cysts - No enhancement on T1 C+
Top Differential Diagnoses
- Chiasmatic/hypothalamic astrocytoma
- Craniopharyngioma
- Ectopic posterior pituitary
- Lipoma
- Germinoma
- Langerhans cell histiocytosis
Pathology
- Mature but dysplastic neuronal ganglionic tissue
Clinical Issues
- Infant with epilepsy or precocious puberty - Cognitive, neuropsychiatric comorbidities common
- Older children with precocious puberty - Often tall, overweight, with advanced bone age
- Shape, size of hamartoma often predicts symptoms, presentation - Large, sessile lesions → seizures - Small, pedunculated lesions → central precocious puberty
Diagnostic Checklist
- If hypothalamic mass in seizure imaging, think hypothalamic hamartoma; if enhancement present, consider astrocytoma

TERMINOLOGY

Synonyms
- Tuber cinereum hamartoma, diencephalic hamartoma
Definitions
- Nonneoplastic congenital gray matter heterotopia in region of tuber cinereum of hypothalamus

IMAGING

General Features

Best diagnostic clue

- Nonenhancing hypothalamic mass contiguous with tuber cinereum

Location

- Tuber cinereum of hypothalamus
- Located between pons/mammillary bodies and hypothalamic infundibulum

Size
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- Variable, few mm to giant (3-5 cm)
```

Morphology

- Sessile or pedunculated mass
- Similar in density/intensity to gray matter

Radiographic Findings

Radiography

- ± suprasellar calcifications, eroded dorsum, enlarged sella (rare)

CT Findings

NECT

- Homogeneous suprasellar mass
        - Isodense → slightly hypodense
        - Cysts and calcification are uncommon
        - ± patent craniopharyngeal canal (very rare)

CECT
```
- No pathologic enhancement
```

MR Findings

T1WI

- Mass located between mammillary bodies and infundibulum
- Isointense → slightly hypointense to gray matter

T2WI

- Isointense → slightly hyperintense (secondary to fibrillary gliosis)

PD/intermediate

- Hyperintense to CSF, slightly hyperintense to gray matter

FLAIR

- Isointense → slightly hyperintense to gray matter

T1WI C+

- Nonenhancing; if enhancing, consider other diagnosis

MRS

- ↓ NAA and NAA/Cr, mild ↑ Cho and Cho/Cr, ↑ myoinositol (mI) and mI/Cr
        - ↓ NAA and ↑ Cho indicate reduced neuronal density and relative gliosis, respectively, compared to normal gray matter
        - ↑ mI/Cr correlates with ↑ glial component and lesion T2 hyperintensity

Imaging Recommendations

Best imaging tool
```
- Multiplanar MR imaging
```

Protocol advice

- Thin-section sagittal and coronal T2W1, T1WI C+ MR

DIFFERENTIAL DIAGNOSIS

Craniopharyngioma
- Most common suprasellar mass in children
- Variable signal intensity cysts (90%), calcifications (90%), and enhancement (90%)
- Longstanding lesion, frequently with short stature and pituitary abnormalities
Chiasmatic/Hypothalamic Astrocytoma
- 2nd most common pediatric suprasellar mass [± neurofibromatosis type 1 (NF1)]
- Hyperintense on T2WI MR ± contrast enhancement (heterogeneous, often vigorous)
- Optic pathway or hypothalamus ± optic tract extension
Ectopic Posterior Pituitary
- Ectopic hyperintense focus on T1WI MR
- Often located along median eminence of hypothalamus
- No normal orthotopic posterior pituitary hyperintensity
Germinoma
- Thickening, abnormal enhancement of pituitary stalk rather than tuber cinereum
- Diabetes insipidus common
- ± multicentric: Suprasellar, pineal, thalamus, basal ganglia
- Early leptomeningeal metastatic dissemination
Langerhans Cell Histiocytosis
- Thickening, abnormal enhancement of pituitary stalk rather than tuber cinereum
- Diabetes insipidus common
- Look for lytic bone lesions in typical locations
Lipoma
- Hyperintense fat signal on T1WI MR
- Hypointense on STIR or fat-saturated sequences

PATHOLOGY

General Features

Etiology

- Neuronal migration anomaly (occurs between gestational days 33-41)
- Affects normal hypothalamic regulation of autonomic, endocrine, neurologic, behavioral functions
- Pathogenesis of precocious puberty-induced sexual precocity
        - ± luteinizing hormone-releasing hormone (LHRH) granules in hamartoma/connecting axons in some
        - Activating astroglial-derived factors in tumors may stimulate endogenous LHRH secretion if no intratumoral LHRH granules
- Shape and size of hamartoma postulated to predict symptoms
        - Large, sessile lesions → seizures
        - Small, pedunculated lesions → central precocious puberty (CPP)
        - Presentation with both seizures and CPP common

Genetics

- *GLI3*mutation
        - Pallister-Hall syndrome (PHS)
                  - Hamartoma or hamartoblastoma of tuber cinereum; often large mass
                  - Digital malformations (short metacarpals, syndactyly, polydactyly)
                  - Other midline (epiglottis/larynx) and cardiac/renal/anal anomalies
        - Greig cephalopolysyndactyly syndrome (GCPS)

Staging, Grading, & Classification
- Valdueza classification - Pedunculated, CPP or asymptomatic - Originates in tuber cinereum - Originates in mammillary bodies - Sessile, hypothalamus displaced, seizures - More hypothalamic dysfunction and abnormal behavior
Gross Pathologic & Surgical Features
- Mature neuronal ganglionic tissue projecting from hypothalamus, tuber cinereum, or mammillary bodies
- Pedunculated or sessile, rounded or nodular
Microscopic Features
- Well-differentiated neurons interspersed with glial cells, myelinated/unmyelinated axons, variable amounts of fibrillary gliosis - Hamartoblastomas include primitive undifferentiated cells
- Rare reports of cysts, necrosis, calcifications, fat

CLINICAL ISSUES

Presentation

Most common signs/symptoms

- Luteinizing hormone-releasing hormone (LHRH) dependent CPP presenting at very young age
- Refractory symptomatic mixed seizure types, including gelastic seizures
        - Gelastic seizures are recurrent automatic bursts of laughter without mirth
        - Presentation usually encompasses both epileptic seizures and encephalopathy with behavioral cognitive impairment
        - May progress to partial epilepsy, partial complex seizures, generalized tonic clonic seizures
        - Rarely occur in conjunction with focal cortical dysplasia or hypothalamic astrocytoma
- Other seizure types frequent with hypothalamic hamartoma (HH); always look for HH in child with epilepsy

Other signs/symptoms

- Depression, anxiety common in adult HH patients

Clinical profile

- Infant with gelastic seizures or precocious puberty
- Older children with precocious puberty; tall, overweight, and advanced bone age

Demographics

Age

- Usually present between 1-3 years of age

Sex
```
- No predilection; some reports M > F
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Ethnicity
```
- No predilection
```

Epidemiology

- Of histologically verified lesions, 3/4 have precocious puberty and 1/2 have seizures
- Up to 33% of patients with CPP have HH

Natural History & Prognosis
- Size should remain stable; if growth is detected, surgery/biopsy is indicated - Postsurgical hypothalamic complications include headache, mental slowing, and weight gain
- Symptomatic lesions: Sessile > > pedunculated - Sessile lesions nearly always symptomatic
- Syndromic patients generally do poorly
Treatment
- Medical: Hormonal-suppressive therapy, treat seizures
- Surgical: If medical therapy failure or rapid lesion growth - Endoscopic or transcallosal surgical resection - Recent studies have shown stereotactic laser ablation to have equivalent efficacy to open surgery with fewer complications - Stereotactic radiosurgery and Gamma Knife surgery also potential options - Newer, less invasive techniques include magnetic resonance imaging-guided laser interstitial thermal therapy (MRgLITT)

DIAGNOSTIC CHECKLIST

Consider
- If hypothalamic mass identified in seizure imaging, think HH
Image Interpretation Pearls
- Classic = nonenhancing hypothalamic mass - Isointense to gray matter on T1WI, slightly ↑ signal on T2WI/FLAIR - Hypothalamic astrocytoma, Langerhans cell histiocytosis (LCH), germ cell tumor all show some contrast enhancement

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References

Selected References

Images

Selected Images

Sagittal graphic shows a classic pedunculated tuber cinereum hamartoma interposed between the infundibulum anteriorly and the mammillary bodies posteriorly. The mass resembles gray matter.

Sagittal T1WI MR in a 2-year-old girl with precocious puberty shows a large, pedunculated "collar button" hypothalamic hamartoma (HH) . The lesion is in the classic location between the infundibular stalk anteriorly and the mammillary bodies posteriorly.

Sagittal T2WI MR in a patient presenting with precocious puberty reveals a pedunculated hypothalamic mass located between the median eminence and mammillary bodies . The mass is isointense with cortex, typical of a hamartoma.

Sagittal T1WI C+ MR in the same patient shows the mass does not enhance. This is a classic pedunculated HH. If the lesion enhanced, considerations would include hypothalamic astrocytoma, Langerhans cell histiocytosis, and germ cell tumor.

Sagittal T1WI MR in a 28-year-old woman being evaluated for seizures shows a well-delineated mass that appears to lie within the 3rd ventricle, isointense to gray matter.

Coronal T2WI MR in the same patient shows the sessile mass is located in the hypothalamus and remains isointense with gray matter. The mass projects into, but does not obstruct, the 3rd ventricle. Patients with sessile lesions are more likely to present with gelastic seizures.

Axial FLAIR MR in a 2 year old with a tuber cinereum hamartoma shows a large suprasellar mass that is isointense to the brain parenchyma.

Sagittal T1WI MR in an 8-year-old girl with precocious puberty shows a classic pedunculated "collar button" HH . The lesion is interposed between the infundibular stalk anteriorly and the mammillary bodies posteriorly. HHs are classically isointense with gray matter.

Sagittal T1WI MR in a child with precocious puberty shows a large, lobulated suprasellar mass that is isointense with cortex and clearly separate from the pituitary gland and optic chiasm. The mass is so large it displaces the brainstem posteriorly.

Axial T2WI MR in the same patient shows the mass is heterogeneously hyperintense compared to cortex. HHs can be huge, measuring up to several cm in diameter. A mass of dysplastic, disorganized gray matter was removed at surgery and was consistent with HH.

Additional Images

Sagittal T1 C+ MR shows a nonenhancing sessile mass arising in the hypothalamus and projecting in the posterior suprasellar cistern.

Sagittal T2WI MR demonstrates that the lesion is slightly bright.

Axial T1 C+ MR reveals nonenhancing hamartoma in the suprasellar cistern.

Coronal T1 C+ MR shows a left-sided nonenhancing hamartoma in the substance of the hypothalamus.

Axial T2WI MR confirms that the mass is isointense to gray matter.

Sagittal T1WI MR demonstrates a huge tuber cinereum hamartoma.

Axial NECT shows large atypical tuber cinereum hamartoma containing a calcification .

Sagittal T1WI MR in a 36-year-old woman being evaluated for seizures shows a well-delineated mass that appears to lie within the 3rd ventricle.

Coronal thin-section IR shows the mass is actually in the hypothalamus. The mass is clearly isointense with gray matter.

Coronal T2WI MR in the same patient shows the mass remains isointense with gray matter and elevates, but does not obstruct, the 3rd ventricle.

Coronal FLAIR in the same patient shows the lesion appears slightly hyperintense relative to cortex. The mass did not enhance following contrast administration. This is a classic sessile HH.

Sagittal FIESTA MR in a 2 year old with seizures and an HH shows the relationship of the hypothalamic mass with adjacent structures. FIESTA eliminates CSF flow artifact and provides high spatial resolution evaluation of suprasellar lesions with a CSF interface.

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KEY FACTS

Terminology

Imaging

Top Differential Diagnoses

Pathology

Clinical Issues

Diagnostic Checklist

TERMINOLOGY

Synonyms

Definitions

IMAGING

General Features

Best diagnostic clue

Location

Size

Morphology

Radiographic Findings

Radiography

CT Findings

NECT

CECT

MR Findings

T1WI

T2WI

PD/intermediate

FLAIR

T1WI C+

MRS

Imaging Recommendations

Best imaging tool

Protocol advice

DIFFERENTIAL DIAGNOSIS

Chiasmatic/Hypothalamic Astrocytoma

Ectopic Posterior Pituitary

PATHOLOGY

General Features

Etiology

Genetics

Staging, Grading, & Classification

Gross Pathologic & Surgical Features

Microscopic Features

CLINICAL ISSUES

Presentation

Most common signs/symptoms

Other signs/symptoms

Clinical profile

Demographics

Age

Sex

Ethnicity

Epidemiology

Natural History & Prognosis

Treatment

DIAGNOSTIC CHECKLIST

Consider

Image Interpretation Pearls

References

Selected References

Images

Selected Images

Additional Images

35 KiB

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