Case study of monosymptomatic delusion of unpleasant body odor with structural frontal abnormality.

We report a 63-year-old man with a monosymptomatic delusion of unpleasant body odor contracted at the age of 61 years, who believed that his body reeked of some type of paint. He had symmetrical atrophy in the bilateral frontal lobes of unknown etiology on MRI. Further, quantitative rCBF measurement with SPECT brain scan using 99mTc-HMPAO showed relative hypoperfusion localized in the bilateral frontal lobes. EEG, neurological and neuropsychological tests were all normal, including the WAIS-R and Wechsler Memory Scale tests. However, he showed poor results on the Wisconsin Card Sorting test, presumably on account of frontal dysfunction, attaining only two categories with frequent perseverative errors. Although it is undetermined whether the illness in this case can be classified as organic delusional syndrome or paranoid disorder according to DSM-III-R criteria, these results imply that delusions are associated with frontal lobe abnormality.