Periventricular CNS germinoma

Case contributed by A.Prof Frank Gaillard

Presentation

Headache. Young asian male.

Patient Data

Age: 30 years
CT

Obstructive hydrocephalus at the level of the foramen of Monro with periventricular white matter hypoattenuation consistent with transependymal CSF leakage and significant mass effect.

Multifocal nodular regions of increased attenuation surrounding the anterosuperior aspect of both lateral ventricles, third and fourth ventricles. No calcification. Superior to the mass lesion at the foramen of Monro there is a cystic component which to represent fluid within a dilated cavum septum pellucidum. Fourth ventricle is partially effaced.

Conclusion: CT findings are consistent with tumour; given the hyperattenuation and pattern of spread lymphoma is favoured. 

MRI

Nodular/lobulated vividly enhancing material which is relatively T2 hypointense and corresponds to the mildly hyperdense lesions on CT is again identified extensively involving the ependymal surfaces of the frontal horns, third ventricle and fourth ventricle. These lesions have similar/ slightly lower ADC values to normal white matter (i.e. <750 x 106 cm2/s). Abnormal enhancement also extends along the cerebral aqueduct and obstructs the foramen of Monro bilaterally. This causes obstructive hydrocephalus. There is extensive periventricular T2 hyperintensity surrounding the lateral, third and fourth ventricles. Lateral ventricular dilation has marginally improved since the insertion of bilateral frontal extraventricular drain tubes. 

Conclusion: Lymphoma is the favoured diagnosis. The alternative diagnostic considerations would be granulomatous disease or subependymal spread of a primary or metastatic malignancy including germinoma, given the extensive third ventricular involvement. 

Pathology

Histology

The sections show scattered granulomas with adjacent lymphocytes and plasma cells. In addition, there is a proliferation of tumour cells. These form aggregates and singly. The tumour cells are large in size. They have enlarged clefted and hyperchromatic nuclei, focal prominent nucleoli and scanty cytoplasm.

The tumour cells are positive for: c-kit, placental alkaline phosphatase (PLAP) and CD10. Sparse cells are also CD15 positive.

They are negative for: AE1/3, CAM5.2, CD20, PAX-5, CD3, CD4, CD5, CD8, CD30, CD34, CD43, CD45, CD79a, CD138, bcl-2, bcl-6, MUM1, ALK-1, TdT, myeloperoxidase, lysozyme, c-Myc, EBER-CISH, CAM5.2, GFAP, S-100, SOX10, melan-A and synaptophysin.

The features are in keeping with germinoma. No other germ cell elements are seen. B-HCG and A-fetoprotein are negative. It is not possible to tell on histology alone whether this is primary or metastatic tumour and clinical correlation is required to make this distinction.

NB: Lymphoma has been excluded. 

Case Discussion

Germinomas tend to be confined to the pineal region or suprasellar / infundibular recess, although the entire floor of the third ventricle is not infrequently involved. Paraventricular parts of the basal ganglia and thalamus is however a feature in 5-10% of cases, more frequently seen in Asian populations. 

 

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Case information

rID: 47398
Case created: 15th Aug 2016
Last edited: 22nd Aug 2016
Inclusion in quiz mode: Included

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