Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Sample Question #40 Next Question Previous question

Answer: B (Negri body)  Level of difficulty: 1 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Negri body  is the pathognomonic inclusion body in rabies as in this case. The are sharply delineated, round to oval, eosinophilic, neuronal cytoplasmic inclusions and was 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. [Click here to see a case of rabies]

• Lewy body is the inclusion that would be found in Parkinson's disease and diffuse Lewy body disease. They can be found in other neurodegenerative conditiosn. These inclusions are present predominantly in the substantia nigra in Parkinson's disease. In diffuse Lewy body, their distribution is more widespreaded. They are concentric hyaline cytoplasmic inclusions characterized by a clear ahlo around a dense central region. Most of them occur as single inclusion but some neurons may have multiple. In contrast to the classical Lewy body in the substantia nigra that can be easily identified by routine hematoxylin-eosin staining, cortical Lewy bodies are difficult to be seen. Lewy bodies bear immunoreactivity for antibodies against neurofilament proteins, ubiqitin and, particularly, synuclein. These inclusions cannot be demonstrated by immunohistochemistry for tau protein..

• Buschino body is an artifact due to prolonged submersion in formalin. Morphologically, they appear as irregular "cracks" that contains a small amount of pale bluish-gray amorphous material.

• Neurofilament tangles can be found in Alzheimer's disease and other neurodegenerative entities as well as non-neurodegenerative entities such as cortical dysplasia. It can be well demonstrated by silver stains such as Bielschowski, Bodian, and Gallya stain as well as immunohistochemistry against tau protein. Ultrastructurally, they are composed of 22 nm-thick paired helical filaments. Biochemically, these filaments contain altered form of tau protein.

• Enigmatic bodies 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.

Comment: KarMing-Fung@ouhsc.edu