NQ-054
Answer:
(C) Occipital encephalocele
Pathology of the cases:
The brain seems to be composed in a larger segment and a smaller segment
and the smaller segment is darker and appeared congested. The gyral pattern of
the smaller part is that of the cerebral hemisphere. It is also bi-lobed and
symmetrically separated. This is a case of occipital encephalocele.
Dysplastic
gangliocytoma of the cerebellum (Lhermitte-Duclos disease): This is is a
condition featured by disorganized cerebellar folia leading to characteristic,
thickening of the cerebellar folia. Although the cerebellar folia are thickened,
the general architecture is maintained. In the present specimen, the gyral
pattern is that of that cerebral hemisphere and so it is not Lhermitte-Duclos
disease. It has features of both malformation and neoplasm. It is discovered
typically in the 3rd and 4th decades and is associated
with Cowden syndrome and linked to germline mutations in
PTEN gene.
[Click here to see an image online]
Glioma:
Although diffuse glioma can enlarge a portion of the brain but it is usually
asymmetrical. In addition, it would not split a brain into a smaller portion and
a larger portion.
Rhombencephalosynapsis: This is a condition characterized by two cardinal
features: missing cerebellar vermis and
apparent fusion of the cerebellar hemispheres at the midline. It can be complete
or partial. It can occur in isolation or in combination with malformation of the
central nervous system or outside the central nervous system. The current
specimen clearly has splitting and the smaller portion of the brain is clearly
composed of cerebral tissue but not cerebellar tissue.
[Click here to see MRI images online]
Lissencephaly:
There is no loss of gyral formation to justify this diagnosis.