NQ-059a Answer: (B) 2 month old infant

NQ-059b Answer: (B) Gliosis

Diagnosis: Thalamic gliosis

Neuroanatomy: Based on the amount of myelin present at the white matter, this is a post-natal brain less than 6 months old. It could be 2 months old post-natal. However, one must take into consideration that chronically ill infants often have a reduction in white matter and relatively slow myelination in comparison to normal infants. Fetus at 32 weeks of gestation has very little, if any, myelin in the cerebral hemisphere. A 1 year old infant will have a lot more myelin to the point that the brain is largely myelinated.  

Gliosis: The pathologic changes are delimited by the arrows. In essence, there is a white rubbery changes involving bilateral thalamus with extension to the surrounding white matter. Bilateral thalamic gliosis is not a rare finding at autopsy. Thalamic neurons are vulnerable for hypoxic-ischemic insults in the premature and term newborn. They are also vulnerable to damage in utero when the mother sustains a cardiorespiratory or hypotensive event during pregnancy. The image being shown is classic for chronic lesion and is characterized by atrophy, firmness, and a chalky-white appearance. The rubbery firmness is due to gliosis.  

Demyelinating process: It is the thalamus, which is composed predominantly of gray matter that is affected. Demyelinating diseases typically affect white matter.

Leukodystrophy: The myelination is incomplete but relatively well myelinated areas are also present. This makes this case unlikely for leukodystrophy.

Neoplastic: The overall gross features are that of a gliosis. Near symmetrical involvement of the thalamus by a neoplastic process is uncommon.

Neurodegeneration: Neurodegenerative diseases are often associated with loss of neurons and gliosis but never to this extent.