Neuroradiology #22 – Flashcard

What do you see on these images?

Click here to see the answer

Oligodendroglioma

CT scan shows a large calcified lesion. MRI shows a large cortical-based high T2 lesion with cystic component and dark T2 foci corresponding to the calcifications. Post-contrast images show patchy enhancing areas.  

Differential Diagnosis

DNET (usually may calcify) ganglioglioma (cystic areas, enhancing solid component, may calcify).

Neuroradiology #17 – Long case

Regarding the following images:

Where is the abnormality?

Bilateral asymmetrical temporal and inferomedial frontal lobes and insular cortices

What is it like?

Abnormal CT hypodensity and high FLAIR signal intensity of the affected white matter and cortex

What is the differential diagnosis?

Herpes encephalitis: affects the limbic system bilaterally, temporal lobes, insular cortices and inferolateral frontal lobes. May progress to hemorrhage. Basal ganglia is typically spared

Paraneoplastic tumor-related limbic encephalitis and autoimmune limbic encephalitis: tumour-related limbic encephalitis and autoimmune limbic encephalitis: autoimmune encephalitis. Same distribution as herpes encephalitis but the basal ganglia is frequently involved. Hemorrhage is uncommon

What is the final diagnosis?

Herpes encephalitis

Neuroradiology #15 – Long case

42-year-old male:
* Presenting with dizziness, vertigo and loss of coordination

What is it?

A focal expansile single lesion.

How is it like?

* Nodular
* Solid
* Hyperdense
* With moderate perilesional edema and mass effect deforming the 4th ventricle without signs of active hydrocephalus (not shown)
* With avid enhancement

Where is it?

Left posterior fossa.

Is the lesion intraaxial (cerebral hemisphere) or extraaxial (cerebellopontine angle)?

TIPS

Suggestive of extraaxial location:
1) Peripheral location and wide dural contact
2) Changes in the adjacent skull vault bone
3) Dural Tail

Definitive for extraaxial location:
1) CSF cleft.
2) Interposed vessels, cortex or dura.

The lesion is intraaxial, located in the left cerebellar hemisphere.

Which are the differentials for intra- and extraaxial posterior fossa tumours?

DIFFERENTIAL DIAGNOSTIC FOR INTRAAXIAL POSTERIOR FOSSA TUMOUR

* HEMANGIOBLASTOMA: Most frequent posterior fossa primary tumour in adults. Strong association with von Hippel Lindau disease. Cystic tumour with mural peripheral solid avidly enhancing nodule. Perilesional pathologic vessels.

* METASTASES: Most frequent posterior fossa tumour in adults. Expanisve focal lesion, single or multiple, well defined, solid-necrotic, great edema, and mass effect.

* GLIOMA: Pilocytic astrocitomas (cystic tumour with solid mural nodule) and diffuse brainstem gliomas (often low-grade, infiltrative, ill-defined lesions without enhancement) much more common in peadiatric population. High-grade gliomas (infiltrative ill-defined lesions with heterogeneous enhancement and necrosis) are uncommon in the posterior fossa.

* MEDULLOBLASTOMA: Paediatric population (more common): Intraventricular, midline; young adults; parenchymal, paramedial, focal solid enhancing lesion. Different subtypes that share hypercellularity as main feature: CT hyperdense, T2 Hypointense and difussion restriction. High propensity for CSF dissemination.

* LYMPHOMA: Focal solid enhancing single lesion or multiple cloud-like enhancing lesions. Hypercellularity as main feature: CT hyperdense, T2 hypointense and diffusion restriction.

* SUBEPENDYMOMA: Adults, intraventricular 4th ventricle. Plastic. None or little enhancement.

* EPENDYMOMA:Paediatric population: intraventricular posterior fossa; young adults: supratentorial periventricular. Plastic, heterogeneous, solid-necrotic, enhancing tumour.

DIFFERENTIAL DIAGNOSTIC FOR EXTRAAXIAL POSTERIOR FOSSA TUMOUR

* MENINGIOMA: Calcifications and bone hyperostosis

* SCHWANNOMA: Intralesional cyst and bone remodelling

* EPIDERMOID: No enhancement, restricted diffusion

* ARACHNOID CYST: CSF behaviour

MAIN CAUSES OF CT HYPERDENSITY

* Mineralization
* Hemorrhage
* Hypercellularity
* Melanin

The images, now supported by diffusion and ADC map, highly suggest and hypercellular tumour

There are two most reasonable diagnostics.

Which are the two most reasonable diagnostics?

MEDULLOBLASTOMA AND LYMPHOMA : Could be appropiate diagnositc options for a lesion with this semiology.
The final histologic diagnosis was: Primary CNS lymphoma

MAIN BRAIN LESIONS WITH CHARACTERISTIC DIFFUSION RESTRICTION

* Abscess
* Lymphoma
* Acute infarct
* Epidermoid

Special tip


In the DSC Perfusion sequence:

* Low relative cerebral blood volume (rCBV) assessed in the colour maps
* T1 Leakage effect assessed in the curve could have helped in the preoperative diagnostic of lymphoma against medulloblastoma.