Final Diagnosis -- Motor Neuron Disease with Basophilic Inclusions

FINAL DIAGNOSIS:

MOTOR NEURON DISEASE WITH BASOPHILIC INCLUSIONS

DISCUSSION:

Motor neuron disease (MND) is associated with a number of intracellular inclusion bodies within surviving motor neurons. In both sporadic and familial MND, Bunina bodies, skein-like inclusions and hyaline inclusions, some of which resemble Lewy bodies, may be seen (1). In Guam-type MND (2), post encephalitis lethargica-related MND (3) and occasional cases of familial MND with mutations in the SOD-1 gene (4), neurofibrillary tangles have been demonstrated. In addition, there have been a few reports (mainly in young individuals) of MND with basophilic cytoplasmic inclusions (5-11). MND with basophilic inclusions appears to be a distinctive histopathological subtype, characterized by circumscribed intraneuronal basophilic inclusions within motor neurons, but also widely distributed within the cerebral cortex, basal ganglia, brainstem and cerebellar nuclei. Unlike the more common MND-inclusions, these basophilic inclusions are largely negative for ubiquitin, although a few show speckled immunoreactivity. Most reported cases presented with rapidly progressive motor weakness, predominantly in young women (5-8). These cases (5-8), together with ours, have a mean age at onset of 19 years and mean disease duration of 12 months (excluding ventilated cases). In addition, there have been three further reports of MND with basophilic inclusions in Japanese men (9-11), who despite having similar pathology, had an mean age of onset of 47 years and duration of illness of about 7 years (excluding a ventilated case). Most cases have presented with purely motor features, although a minority of cases have autonomic dysfunction or dementia. None of the reported cases have had a family history of MND.

References

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