Progressive nonfluent aphasia: A rare clinical subtype of FTLD‐TDP in Japan

Progressive nonfluent aphasia (PNFA) is a clinical subtype of frontotemporal lobar degeneration (FTLD). FTLD with tau accumulation (FTLD‐tau) and FTLD with TDP‐43 accumulation (FTLD‐TDP) both cause PNFA. We reviewed clinical records of 29 FTLD‐TDP cases in the brain archive of our institute and found only one case of PNFA. The patient was an 81‐year‐old male at death. There was no family history of dementia or aphasia. He presented with slow, labored and nonfluent speech at age 75. Behavioral abnormality and movement disorders were absent. MRI at age 76 demonstrated atrophy of the perisylvian regions, including the inferior frontal gyrus, insular gyrus and superior temporal gyrus. The atrophy was more severe in the left hemisphere than the right. On post mortem examinations, neuronal loss was evident in these regions as well as in the substantia nigra. There were abundant TDP‐43‐immunoreactive neuronal cytoplasmic inclusions and round or irregular‐shaped structures in the affected cerebral cortices. A few dystrophic neurites and neuronal intranuclear inclusions were also seen. FTLD‐TDP showing PNFA seems to be rare but does exist in Japan, similar to that in other countries.