Saturday 1 October 2016

Medulloblastoma MRI

Clinical Details  : From last one and half months has tremolousness involving left arm, episodic associated with facial twitching, unsteadiness of gait and severe headaches associated with vomiting. No significant illness in the past. Examination shows bilateral papilloedema, brisk reflexes, plantars flexor.

MR study of brain reveals an ~ 35x37mm well defined solid signal intensity tumor in the region of fourth ventricle causing moderate obstructive hydrocephalous, peri ventricular ooze of Csf. Diffuse cerebral odema. Prominent Sub Arachnoid space around optic nerves owing to raised ICT.
Cysts noted at the periphery of lesion, solid component show mild patchy enhancement on post contrast, restricted diffusion on Dw images.

Imaging wise primary diagnosis : Medulloblastoma.

No DDs suggested.  

Operated with posterior fossa craniotomy. E/o complete excision of lesion. No major intra / extra axial bleed.
And here is...


Specimen         :     Biopsy – 4th ventricular SOL.
Gross Appearance    :     The specimen consists of few soft to friable fragments of dull grey-white tissue; together measuring 3.0X2.5X1.3 cm. The entire tissue is submitted for processing.
Codes : A and B.

Microscopy        :     Sections A and B both show fragmented bits of monotonous undifferentiated cellular neoplasm of probable medulloblastic origin. The tumour consists of cohesive sheets of fairly monotonous appearing, intermediate sized, round to oval cells having hyperchromatic, minimally pleomorphic nuclei with coarse chromatin and scanty eosinophilic cytoplasm. Few foci reveal nuclear moulding, while many areas show elongation of nuclei. The neoplasm in couple of foci show vague nodular configuration with nodules comprising of rather pale-stained neoplastic cells. The interstitium at places appears desmoplastic and shows compressed congested blood vessels. An occasional focus shows mitosis. No classical               Homer-Wright rosettes seen. The background shows minimal fibrillary appearance. Also seen are couple of fragments of cerebellar parenchyma.

Final Diagnosis :  Embryonal malignant small blue cell tumor – Medulloblastoma; undifferentiated.

Adv. :     Ancillary IHC studies are mandatory for confirmation and definite lineage typing.

Similar Cases


Syn: MB, Posterior fossa PNET, PNET – MB,
A highly cellular embryonal cell tumor.
Age group : common in children, ~75% diagnosed by 10 years.
3 times more common in males.

Intraventricular – 4th ventricular roof is a typical and most common location. A most common posterior fossa tumour in children.
Lateral origin – Cerebellar hemisphere is an atypical location common in older children and adults.

Size vary, average size ranges between 3- 5cm at the time of presentation.
On Non contrast CT, solid 4th ventricle mass, hyperdense, calcifcaiton seen in ~20% cases, small intra tumoural cysts, necrosis in ~50% cases.
On MR signal on T1 iso - hypo intense to cortical grey matter on T1 , iso – hyperintense on T2w and FLAIR. High signal on diffusion attributed to its dense, highly cellular nature.
An associated Obstructive hydrocephalus is common seen in ~ 95% cases.
Usually mild to moderate and homogenous enhancement, may show patchy heterogeneous enhancement due to areas of necrosis.
On MR Spectroscopy, NAA reduced or absent as it’s a non neuronal tumour, raised choline.

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