NQ-090a Answer: (B) Cerebellar folia
Diagnosis: Cerebellum obtained from a patient who died of rabies.
Neuroanatomical consideration: The smaller cells are the internal granule layer and the larger cells are the Purkinje cells. The neuropil on the right with only a few nuclei present is the molecular layer. The overall structure is that of the cerebellar folia.
Pathology of this case: The sharply demarcated, brightly eosinophilic inclusions are the pathognomonic Negri bodies in rabies. These sharply delineated, round to oval, eosinophilic, neuronal cytoplasmic inclusions were first described by Negri in 1903. These inclusions are often solitary but may also be multiple in a single neuron. They tend to be found in large neurons particularly the Perkinje cells and pyramidal cells in the hippocampus. In contrast to other viral encephalitis, the intensity of chronic inflammatory cell infiltration in Rabies is usually minimal to, at most, mild. Interestingly, Negri bodies are more likely to be found in areas with minimal or no inflammatory cell infiltration like the one being shown here. Under the electron microscopy, Negri bodies are formed condensation of excessive viral nucleocapsid material. [Click here to see online electron micrographs of Negri body and Rabies virus]
Buschino body: This is an artifact due to prolonged submersion in formalin. They are common in brains that have been submersed in formalin for a prolonged period, usually months to years, in formalin. Morphologically, they appear as irregular and often elongated "cracks" that contain a small amount of pale bluish-gray amorphous material.
Enigmatic body: These are large, membrane bound bodies that often displace the Golgi apparatus. They have electron dense periphery and acid phosphatase activity. Enigmatic bodies are believed to be dilated lysosomes. These structures appear as cytoplasmic vacuoles in corticotrophs (basophils) in pituitary glands. [Click here to see an online link for more information]
Polyglucosan bodies: The salient
feature of adult polyglucosan body disease is the accumulation of polyglucosan
bodies in the central nervous system. Polyglucosan bodies can also be found in
other locations such as sweat glands which provides a convenient site for
biopsy. Histologically, polyglucosan bodies are almost identical to corpora
amylacea and they are strongly positive on PAS stain due to its high content of
polysaccharide. Mutations in GBE1 gene cause adult polyglucosan body
disease. [Click here to see an image
with HE stain]
[Click here to see an image of polyglucosan bodies]
[Click here to see an online link on the genetics of
polyglucosan body disease]
[Click here to see online information]
[Click here to see an interesting case that
clinically mimics glioma]