Case 1

A patient aged in the late sixties with neither significant past medical history nor family history of neurological disease was referred to our hospital with gait disturbance and dementia with symptoms including frequent disorientation over 3 years. A neurological examination revealed no ataxia, sensory disturbances or urinary incontinence. The patient's Mini-Mental State Examination (MMSE) Score was 29. A brain MRI showed moderate cerebral and cerebellar atrophy and high-intensity areas in the cerebral white matter in the T2-weighted and fluid-attenuated inversion recovery (FLAIR) images (figure 1A). The MRI diffusion-weighted imaging (DWI) revealed a high-intensity signal in the corticomedullary junction, and these areas showed isointensity and low intensity on the ADC map (figure 1A). A cerebrospinal fluid (CSF) examination showed no pleocytosis or protein elevation and a normal glucose level. The nerve conduction studies were normal.

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Figure 1

(A) The results of brain imaging. Head MRIs of Case 1, Case 2 and Case 3. Axial image of T2-weighted MRI, fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging and ADC map; ADC map of Case 3 could not be computed because MRI system was old. cerebral hemisphere level section and cerebellar peduncle level section. (B–D) Histopathological study results of skin biopsy samples. (B) Immunohistochemical study of Case 1, Case 2 and Case 3. Immunostained samples of adipocyte, fibroblast and sweat gland cells with anti-ubiquitin antibody using the DAB technique, and immunofluorescence study with an anti-ubiquitin antibody with DAPI, immunofluorescence study with anti-SUMO1 and anti-ubiquitin antibodies, and immunofluorescence study with anti-p62 and anti-ubiquitin antibodies. Ubiquitin-positive intranuclear inclusions were observed in the nuclei of the adipocytes in Case 1 (white arrows), fibroblasts in Case 2 (green arrows) and sweat gland cells of Case 3 (red arrows). The intranuclear inclusions were double-labelled with ubiquitin and SUMO1 in sweat gland cells of Case 1 (white arrowheads), adipocytes in Case 2 (green arrowhead) and fibroblasts in Case 3 (red arrowhead), and double-labelled with ubiquitin and p62 in fibroblast of Case 1 (white asterisk), sweat gland cells of Case 2 (green asterisk) and adipocytes in Case 3 (red asterisk). Scale bars=10 μm. (C) Immunohistochemical study of normal control, Alzheimer's disease and Binswanger's disease subjects with anti-ubiquitin antibody. Scale bars=10 μm. (D) Electron microscopic images of intranuclear inclusion of fibroblasts of Case 1, Case 2 and Case 3 at lower magnification (black arrows) and higher magnification. Scale bars=2 μm (Low magnification) and 500 nm (high magnification).

Case 2

The patient aged in seventies consulted a neurologist for dementia. The patient had a history of prostate enlargement, and father was diagnosed with Parkinson's disease. At the age of 65 years, this patient noticed unsteady gait and experienced difficulty remembering people's name. Then, the patient began talking to oneself, complained of transient blindness, and began to eat flowers instead of food. A neurological examination revealed dementia, limb-kinetic apraxia, constructional apraxia, dysarthria, wide-based gait and constipation. A brain MRI showed atrophy in the cerebellum and high-intensity areas in bilateral cerebral white matter on the T2 and FLAIR (figure 1A), a high-intensity signal in the corticomedullary junction on the DWI and isointensity and low intensity on the ADC map (figure 1A). An EEG showed a diffuse slow α background, and high voltage θ–δ waves appeared diffusely.

Case 3

A patient aged in the late sixties presented with abnormal behaviour, such as absentmindedly standing naked in a room. The patient had a past history of gastric ulcer and diabetes but no family history of neurological diseases. The neurological examination revealed miosis with normal light reflex, decreased tendon reflexes and a positive bilateral Babinski sign. The patient's MMSE score was 29. The results of a brain MRI were identical to Case 1 and Case 2 (figure 1A). A CSF examination showed no pleocytosis but did show a slight protein elevation and a slight glucose elevation. An EEG showed no abnormal activity.

Genetic testing of the FMR1 gene for these three cases revealed no expanded CGG premutation. We performed skin biopsies as part of the differential diagnosis for leukoencephalopathy, with the expectation of NIID.

Skin biopsy findings

In the anti-ubiquitin stained sections using the DAB technique (figure 1B) and immunofluorescence technique (figure 1B,C), intranuclear inclusions were identified in the adipocytes, fibroblasts and sweat gland cells of the three patients and no intranuclear inclusion was observed in the normal control or Alzheimer's disease and Binswanger's disease groups (figure 1B,C). The intranuclear inclusions in the dermal cells of these patients also showed anti-SUMO1 and anti-p62 immunoreactivity (figure 1B). Electron microscopy revealed that the intranuclear inclusions of the three patients were composed of filaments and showed no limiting membranes (figure 1D). These results were similar to the results previously reported for NIID neuronal cells.1–3