bs_bs_banner Neuropathology 2016; ••, ••–•• doi:10.1111/neup.12327 Case Report An autopsied case of MM1 + MM2-cortical with thalamic-type sporadic Creutzfeldt-Jakob disease presenting with hyperintensities on diffusionweighted MRI before clinical onset Yasushi Iwasaki,1 Keiko Mori,2 Masumi Ito,2 Maya Mimuro,1 Tetsuyuki Kitamoto3 and Mari Yoshida1 1 Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, 2Department of Neurology, Oyamada Memorial Spa Hospital, Yokkaichi and 3Department of Neurological Science, Tohoku University Graduate School of Medicine, Sendai, Japan A 78-year-old Japanese man presented with rapidly progressive dementia and gait disturbances. Eight months before the onset of clinical symptoms, diffusion-weighted magnetic resonance imaging (DWI) demonstrated hyperintensities in the right temporal, right parietal and left medial occipital cortices. Two weeks after symptom onset, DWI showed extensive hyperintensity in the bilateral cerebral cortex, with regions of higher brightness that existed prior to symptom onset still present. Four weeks after clinical onset, periodic sharp wave complexes were identified on an electroencephalogram. Myoclonus was observed 8 weeks after clinical onset. The patient reached an akinetic mutism state and died 5 months after onset. Neuropathological examination showed widespread cerebral neocortical involvement of fine vacuole-type spongiform changes with large confluent vacuole-type spongiform changes. Spongiform degeneration with neuron loss and hypertrophic astrocytosis was also observed in the striatum and medial thalamus. The inferior olivary nucleus showed severe neuron loss with hypertrophic astrocytosis. Prion protein (PrP) immunostaining showed widespread synaptic-type PrP deposition with perivacuolar-type PrP deposition in the cerebral neocortex. Mild to moderate PrP deposition was also observed extensively in the basal ganglia, thalamus, cerebellum and brainstem, but it was not apparent in the inferior olivary nucleus. PrP gene analysis showed no mutations, and polymorphic codon 129 showed methionine homozygosity. Western blot analysis of protease-resistant PrP showed both type 1 scrapie type PrP (PrPSc) and type 2 PrPSc. Based on the relationship between the neuroimaging and pathological Correspondence: Yasushi Iwasaki, M.D.; Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University; 1-1 Yazakokarimata, 480-1195 Nagakute, Japan. Email: iwasaki@sc4.so-net.ne.jp Received 18 February 2016; revised and accepted 30 June 2016. © 2016 Japanese Society of Neuropathology findings, we speculated that cerebral cortical lesions with large confluent vacuoles and type 2 PrPSc would show higher brightness and continuous hyperintensity on DWI than those with fine vacuoles and type 1 PrPSc. We believe the present patient had a combined form of MM1 + MM2cortical with thalamic-type sporadic Creutzfeldt-Jakob disease (sCJD), which suggests a broader spectrum of sCJD clinicopathological findings. Key words: Creutzfeldt-Jakob disease, diffusion-weighted MRI, MM2-cortical-type, MM2-thalamic-type, prion protein. INTRODUCTION Clinicopathological presentation of sporadic CreutzfeldtJakob disease (sCJD) is influenced by several factors, particularly the patients’ prion strain and polymorphism of the prion protein (PrP) gene.1,2 According to the genotype of the methionine (M)/valine (V) polymorphism at codon 129 of the PrP gene, and the physicochemical properties of type 1 scrapie type PrP (PrPSc) and type 2 PrPSc, sCJD has been classified into six subtypes: MM1, MM2, MV1, MV2, VV1 and VV2.1,2 MM2-type sCJD is further divided into two different clinicopathological phenotypes, MM2-cortical-type and MM2-thalamic-type.1,2 Although this classification system is helpful in the identification and understanding of major sCJD subgroups, there are some individual cases that are difficult to classify on this basis, such as those that present with two combined subtypes.3–5 Comprehensive analyses of clinical and neuropathological findings, as well as analyses of PrP gene and PrP type, should be applied to better understand these atypical cases.1–8 Here, we report a case of suspected MM1 + MM2-cortical with thalamic-type sCJD, presenting with rapidly progressive 2 Iwasaki Y et al. dementia, as well as myoclonus and periodic sharp wave complexes (PSWCs) on an electroencephalogram (EEG). Interestingly, this patient showed cerebral cortical hyperintensity on diffusion-weighted MRI (DWI) before clinical onset. We discuss the relationship between MRI findings and pathological findings, and the clinicopathological aspects with respect to the phenotypic spectrum of both MM1 + MM2-type sCJD and MM2-cortical + thalamic-type sCJD. CLINICAL SUMMARY A 77-year-old Japanese man became aware of dizziness, which spontaneously remitted a few days later. He consulted a local hospital for examination. Although he showed no neurological deficits, MRI was performed in order to exclude the possibility of stroke because he had been administered predonine for the treatment of nephrotic syndrome since the age of 68 years. DWI demonstrated hyperintensities in the right temporal, right parietal and left medial occipital cortices (Fig. 1A). Fluid-attenuated inversion recovery (FLAIR) images also showed very mild hyperintensities in these regions. Apparent diffusion coefficient (ADC) images were not acquired. The patient was diagnosed with cerebral infarction and antiplatelet drugs were started. For the next 8 months, he showed no problems in daily life and no cognitive dysfunction was apparent. However, at 78 years of age, he suddenly showed rapidly progressive dementia and gait disturbances with frequent falls. Two weeks after clinical onset, he was referred to the Department of Neurology, and neurological examination revealed disorientation, sialorrhea, difficulty in conversation and apraxia of the hand. DWI showed extensive hyperintensity in the bilateral cerebral cortex, with the cortical regions of higher brightness that were observed before symptom onset (Fig. 1B). Single-photon emission computed tomography (SPECT) showed reduction of blood flow to the bilateral thalamus (Fig. 2). The right temporal, right parietal and left medial occipital cortices seemed to show slightly decreased blood flow relative to the surrounding cortices. A lumbar puncture was also performed; the CSF sample contained one mononuclear cell/mm,3 24 mg/dL total protein, and 81 mg/dL sugar. Total tau protein and 14-3-3 protein in the CSF were elevated to 2886 pg/mL (cut off level 1300 pg/mL) and 961.87 μg/mL (cut off level 500 μg/mL), respectively. EEG examination performed 4 weeks after clinical onset revealed typical PSWCs. Eight weeks after clinical onset, myoclonus, startle reaction and bilateral Babinski sign were observed. Ten weeks after the onset of major symptoms, the patient reached an akinetic mutism state, and nasal tube feeding was introduced. DWI acquired 3 months after clinical onset showed extensive hyperintensity in the bilateral cerebral cortex; areas of higher brightness persisted in the right temporal, right parietal and left medial occipital cortices (Fig. 1C). ADC images demonstrated hypointensity in the right temporal, right parietal and left medial occipital cortices (Fig. 1D). FLAIR images showed extensive hyperintensity in the bilateral cerebral cortex, particularly in the right temporal, right parietal and left medial occipital cortices (Fig. 1E). Thereafter, a stable general condition continued, but the patient suddenly died of suffocation 5 months after the onset of major symptoms. Autopsy and PrP gene analyses were performed with the informed consent of the patient’s family. METHODS Neuropathological examination The brain was fixed in 20% neutral-buffered formalin for 4 weeks. After brain cutting, the tissue blocks were immersed in 95% formic acid for 1 h to inactivate the prion infectivity. Eight-micrometer-thick sections were mounted, deparaffinized, dehydrated and stained. For routine neuropathological examinations, sections were subjected to HE, KB and Gallyas Braak staining. Immunohistochemical analysis of selected sections were carried out using the antibody 3F4 against PrP (mouse monoclonal, diluted 1:100, Dako, Glostrup, Denmark). The 3F4 antibody is specific to human PrP amino acids 109–112 and recognizes both type 1 PrPSc and type 2 PrPSc.9 The PrP immunostaining protocol used a hydrolytic autoclaving method to enhance the PrP immunoreactivity, and the EnVision amplified visualization method (EnVision plus kit, Dako), as previously described.6,8 Anti-β-protein antibody (mouse monoclonal, diluted 1:100, Dako) and anti-human GFAP antibody (mouse monoclonal, diluted 1:1000, Dako) were also used for immunostaining. Peroxidase-conjugated streptavidin was visualized using 3,3′-diaminobenzidine chromogen (Wako Pure Chemical Industries, Osaka, Japan). Immunostained sections were counterstained lightly with Mayer’s hematoxylin. Western blot analysis of the protease-resistant PrP and PrP gene analysis The cryopreserved right frontal cerebral cortex was homogenized, and Western blot analysis of protease-resistant PrP was performed using 3F4, as previously described.6 Typing of PrPSc was performed according to the sCJD classification system proposed by Parchi et al.2 Furthermore, to investigate the co-occurrence of type 1 and type 2 PrPSc, we carried out an additional experiment using the type 1 PrPSc-specific antibody Tohoku-1 and the type 2 PrPSc-specific antibody Tohoku-2 after protease treatment.9 © 2016 Japanese Society of Neuropathology MM1 + MM2-cortical with thalamic-type sporadic CJD 3 Fig. 1 Chronological head MRI findings. A: Diffusion-weighted MRI (DWI) acquired 8 months before clinical onset shows hyperintensities in the right temporal, right parietal and left medial occipital cortices. B: DWI obtained 2 weeks after clinical onset shows hyperintensities in the bilateral cerebral cortex, along with the same cortical regions that showed higher brightness in the right temporal, right parietal and left medial occipital cortices prior to clinical onset. C: DWI obtained 3 months after clinical onset shows extensive hyperintensities in the bilateral cerebral cortex. Regions in the right temporal, right parietal and left medial occipital cortices still show higher intensity. D: Apparent diffusion coefficient (ADC) images obtained 3 months after clinical onset demonstrate hypointensities in the right temporal, right parietal, and left medial occipital cortices. E: Fluid-attenuated inversion recovery (FLAIR) images obtained 3 months after clinical onset show extensive hyperintensities in the bilateral cerebral cortex, particularly in the right temporal, right parietal and left medial occipital cortices. R: right side. Genomic DNA was extracted from the cryopreserved brain tissue and used to amplify the open reading frame of the PrP gene by PCR. We searched for mutations and investigated the polymorphisms at codons 129 and 219 by restriction fragment length polymorphism analysis, as previously described.6 © 2016 Japanese Society of Neuropathology PATHOLOGICAL FINDINGS Macroscopic findings The brain weighed 1050 g before formalin fixation. Cerebral atrophy with widening of the sulci was observed (Fig. 3A), 4 Fig. 2 Single-photon emission computed tomography (SPECT) findings. The 123I-IMP-SPECT shows blood flow reduction in the bilateral thalamus. Although blood flow in the cerebral cortex and basal ganglia is relatively preserved, the right temporal, right parietal and left medial occipital cortices seem to show slightly decreased blood flow compared to the surrounding cortices. R: right side. particularly in the right hemisphere. In the horizontal sections, the cerebral cortex was generally thin, particularly in the right hemisphere, whereas the basal ganglia and the hippocampus were preserved from atrophy (Fig. 3B). The cerebellum and brainstem showed no apparent atrophy. Depigmentation of the substantia nigra or locus ceruleus was not apparent. Microscopic findings In the cerebral cortex, spongiform change was extensively observed, with both fine vacuoles (Fig. 4A2a, 4B2a) and large confluent vacuoles (Fig. 4A3a, 4B3a) present. In macroscopic loupe images, the vacuoles were recognizable in regions that contained large confluent vacuoles, but difficult to see in regions that contained fine vacuoles (Fig. 4A1b, 4B1b). In each cortical region, either type of spongiform change was observed, with both coexisting in some regions (Fig. 4A4a). Large confluent vacuoles were predominantly seen in the right temporal, right parietal and left medial occipital cortices, all regions in which Iwasaki Y et al. continuous hyperintensity on DWI was observed. Neuron loss with hypertrophic astrocytosis was also extensively observed, more mildly in the regions with large confluent vacuoles than in the regions with fine vacuoles. The insular cortex and entorhinal cortex showed apparent spongiform change with tissue rarefaction, whereas the hippocampus and subiculum showed mild spongiform change without hypertrophic astrocytosis. The caudate nucleus and putamen (Fig. 5A1) showed fine vacuole-type spongiform change with mild neuron loss and hypertrophic astrocytosis. The globus pallidus and lateral thalamus were relatively preserved from spongiform change, gliosis, and neuron loss. The medial thalamus showed spongiform change with moderate neuron loss and hypertrophic astrocytosis (Fig. 5B1). Myelin pallor and hypertrophic astrocytosis were not apparent in the cerebral white matter. In the cerebellum, the molecular layer showed extensive spongiform change with mild atrophy (Fig. 5C1). Mild neuron loss with Bergmann’s gliosis and torpedoes in the Purkinje cell layer were observed. Mild neuron loss was also observed in the granule cell layer. The dentate nucleus was well preserved without gliosis. The cerebellar white matter was preserved without myelin pallor. In the brainstem, neuron loss and gliosis were not apparent in the substantia nigra, pontine nucleus or locus ceruleus. The inferior olivary nucleus showed pseudohypertrophy (Fig. 5D1) and severe neuron loss with hypertrophic astrocytosis (Fig. 5D2). Pyramidal tract degeneration was not observed in the brainstem. Florid plaques or Kuru plaques were not observed. Few neurofibrillary tangles were observed and the distribution corresponded to Braak stage I. Senile plaques, argyrophilic grains and Lewy bodies were not observed. No apparent vascular lesions were recognized. PrP immunohistochemical findings In the cerebral cortex, including the limbic system, PrP deposition of both the synaptic-type (Fig. 4A2b, 4B2b) and perivacuolar-type (Fig. 4A3b, 4B3b) were extensively observed, showing a diffuse fine granular staining pattern Fig. 3 Macroscopic appearance of the brain.A: Cerebral atrophy with widening of the sulci is apparent. The cerebellum shows no apparent atrophy. B: The horizontal section of the cerebrum shows diffuse cerebral cortical atrophy and lateral ventricular dilation, particularly on the right side (right frontal and occipital poles were cryopreserved at autopsy). Scale bars = 10 mm. R: right side. © 2016 Japanese Society of Neuropathology MM1 + MM2-cortical with thalamic-type sporadic CJD 5 Fig. 4 Relationship between the diffusion weighted MRI (DWI) findings and the pathological findings. A: The left medial occipital cortex shows hyperintensity with more high-brightness in part (A1a). The cortical region of hyperintensity with lesser high-brightness (A2) shows fine vacuoles (A2a) and synaptic-type prion protein (PrP) deposition (A2b). The cortical region with more high-brightness (A3; surrounded by a rectangle) shows large confluent vacuoles (A3a) and perivacuolar-type PrP deposition (A3b). In macroscopic loupe images, the vacuoles are easily recognized in regions with large confluent vacuoles but difficult to see in regions with fine vacuoles (Fig. 4A1b, 4B1b). The transitional region of both sites (A4) shows a mixture of both types of spongiform change (A4a) and PrP deposition (A4b). B: Right parietal and medial occipital cortices also show hyperintensity with more high-brightness in certain regions (B1a). The cortical region with less high-brightness in the parietal cortex (B2) shows fine vacuoles (B2a) and synaptic-type PrP deposition (B2b). The cortical region with more high-brightness in the parietal cortex (B3; surrounded by a rectangle) shows large confluent vacuoles (B3a) and perivacuolar-type PrP deposition (B3b). The cortical region with more high-brightness in the medial occipital cortex (surrounded by an oval) also shows large confluent vacuoles and perivacuolartype PrP deposition (pathological findings not shown). A1b, A2a, A3a, A4a, B1b, B2a, B3a: HE staining. A2b, A3b, A4b, B2b, B3b: anti-PrP (3F4) immunostaining. Scale bars = 200 μm. and intense PrP deposits around areas of confluent spongiform change, respectively. In each cortical region, either type of PrP deposition could be observed, with both coexisting in some regions (Fig. 4A4b). Fundamentally, the cortical regions presenting with fine vacuole-type spongiform change showed synaptic-type PrP deposition, whereas the cortical regions presenting with large confluent vacuole-type spongiform change showed perivacuolar-type PrP deposition. Regions with both types of spongiform change showed a mixture of both types of PrP deposition. In the caudate nucleus, putamen (Fig. 5A2), and medial thalamus (Fig. 5B2), moderate synaptic-type PrP deposition was observed. The globus pallidus and lateral thalamus showed generally mild synaptic-type PrP deposition. In the cerebellum, moderate synaptic-type PrP deposition was observed in the molecular and granule cell layers (Fig. 5C2), as well as in the dentate nucleus. In the brainstem, mild synaptic-type PrP deposition was observed in the tegmentum of the midbrain, the substantia nigra and the pontine nucleus. The inferior olivary nucleus showed no apparent PrP immunoreactivity (Fig. 5D3). PrP deposition was not observed in the cerebral and cerebellar white matter. © 2016 Japanese Society of Neuropathology Western blot analysis and PrP gene analysis PrP gene analysis showed no mutations. Methionine homozygosity at codon 129 and glutamic acid homozygosity at codon 219 were identified. Western blot analysis of protease-resistant PrP using the 3F4 antibody showed a predominant type 1 PrPSc band; the unglycosylated band had a relative molecular mass of 21 kDa (Fig. 6A). Additionally, there was a weakly observed type 2 PrPSc band; the unglycosylated band had a relative molecular mass of 19 kDa (Fig. 6A). Western blot analyses using type 1 and type 2 PrPSc-specific antibodies both showed apparent positive bands (Fig. 6B). These findings indicated that both the dominant type 1 PrPSc and the type 2 PrPSc were present together in the patient’s right frontal cerebral cortex. DISCUSSION From this case study, we arrived at the significant conclusion that there can be mixed pathology in sCJD that includes both fine vacuole-type spongiform change with synaptictype PrP deposition, as well as large confluent vacuole-type 6 Iwasaki Y et al. Fig. 5 Representative pathological findings of the subcortical gray matter, cerebellum and brainstem. A: Extensive spongiform change with mild neuron loss and hypertrophic astrocytosis is observed in the putamen (A1). Diffuse synaptictype PrP deposition is observed (A2). B: Spongiform change with moderate neuron loss and hypertrophic astrocytosis is observed in the medial thalamus (B1). Diffuse synaptic-type PrP deposition is also observed (B2). C: Extensive spongiform change with mild atrophy is observed in the molecular layer of the cerebellum. Mild neuron loss in the Purkinje cell layer with Bergmann`s gliosis and mild neuron loss in the granule cell layer are also observed (C1). Diffuse synaptictype PrP deposition is observed in the molecular and granule cell layers of the cerebellum (C2). D: The inferior olivary nucleus shows pseudohypertrophy (D1). Severe neuron loss with hypertrophic astrocytosis is recognized (D2), whereas PrP deposition is not apparent (D3). A1, B1, C1, D2: HE staining. D1: KB staining. A2, B2, C2, D3: anti-PrP (3F4) immunostaining. Scale bars: A1, A2, B1, B2, D2, D3, 200 μm. C1, C2, 500 μm. D1, 5 mm. spongiform change with perivacuolar-type PrP deposition in the cerebral cortex. These pathological findings from the present case suggest that there is a combined MM1 + MM2-cortical-type sCJD.10 Parchi et al. concluded that regions showing fine vacuole-type spongiform change reflect synaptic-type PrP deposition and type 1 PrPSc deposition, whereas regions showing large confluent vacuole-type spongiform change reflect perivacuolar-type PrP deposition and type 2 PrPSc deposition.11 We previously reported that only a small amount of MM2 molecules were present in all MM1-type sCJD cases using Western blot analysis.12 Therefore, it may be more appropriate to determine the MM1 ± 2 type sCJD based on a significant increase of type 2 PrPSc deposition as seen by neuropathological observation instead of Western blot analysis. In terms of the pathogenesis of type 1 + 2 PrPSc combined sCJD cases, it has been speculated that one prion strain occurs first, but later, different strains are produced.13 However, this mechanism is presently unknown. In general, the rapidly progressive clinical course, including myoclonus and PSWCs on EEG, corresponded to the classic-type sCJD (MM1-type sCJD).1,2,6,13 Therefore, this observation suggests that the clinical course of the present case was mainly due to the MM1-type sCJD pathology. In the literature, two case reports similarly recognized hyperintensities on DWI before the clinical onset of CJD.14,15 In one case with MM1-type sCJD, from the ‘Brain Dock’ used to detect asymptomatic brain disease in Japan, hyperintensity on DWI was discovered 2 months before any clinical onset.14 In another case with V180I genetic CJD, hyperintensity on DWI was discovered 3 months before clinical onset.15 The DWI hyperintensities in the cerebral cortices of the CJD patients are speculated to reflect the pathology of the spongiform change, but not gliosis, tissue rarefaction or neuron loss.13 Based on the present case and the previous case reports described above, we suspect that the spongiform changes associated with CJD must begin several months before clinical onset. In the present study, we could only analyze the PrP type in one frozen right frontal cerebral cortex sample. From this analysis, we showed that the dominant type 1 PrPSc and the type 2 PrPSc were combined in this region. However, according to the pathological findings of the present case, several other regions presented with hyperintensity on DWI before clinical onset, including the right temporal, right parietal and left medial occipital cortices; these regions would be expected to show the type 2 PrPSc deposition pattern. If Western blot analyses were performed in these regions, the type 2 PrPSc band pattern may have been observed. Interestingly, these regions showed consistent hyperintensity on DWI in not only the early disease stage, but also in the akinetic mutism state; we speculate that these hyperintensities result from the characteristic type 2 PrPSc deposition in the cerebral cortex. Moreover, the brightness of the hyperintensities was higher in regions that showed large confluent vacuole-type spongiform change compared to regions that showed fine vacuole-type spongiform change. © 2016 Japanese Society of Neuropathology MM1 + MM2-cortical with thalamic-type sporadic CJD Fig. 6 Western blot analysis of PrP. Western blot analysis of the protease-resistant PrP from the cryopreserved right frontal cerebral cortex corresponds to lane 2 and is compared to the PrPs from six patients with prion diseases. Lanes 1, 3, 4 and 6 are patients with MM1-type sporadic Creutzfeldt-Jakob disease (CJD). Lane 5 is a patient with genetic CJD with the V180I mutation. Lane 7 is a patient with Gerstmann-Sträussler-Scheinker disease with the P102L mutation. A: With the 3F4 antibody, PrP migrated as three separate bands that correspond to the diglycosylated (upper band), monoglycosylated (middle band) and unglycosylated forms (lower band). The unglycosylated band appears around 21 kDa in lane 2, but a very weak band also appears around 19 kDa. B: With the type 2 PrPSc-specific antibody (Tohoku-2), PrP migrated as three separate bands in lane 2; the unglycosylated band appears around 19 kDa. Analysis with the type 1 PrPSc-specific antibody (Tohoku1) also showed positive findings; the unglycosylated band appears around 21 kDa (data not shown). In future cases, we may be able to speculate on which types of PrPSc are deposited in the cerebral cortex according to the brightness and duration of the hyperintensities on DWI, before relying on autopsy or Western blot analysis. Furthermore, we also speculate that, in the present case, the CJD pathology was potentially initiated by the MM2-cortical-type before clinical onset. However, the patient showed a rapidly progressive clinical course after the initial onset, likely due to the MM1-type pathology that occurred later. Why the MM2-cortical-type and the MM2-thalamic-type share the same codon 129 genotype and PrP type, but have different clinicopathological phenotypes, is puzzling, and their underlying mechanisms remain unknown.1,2 Although Parchi et al. suggested that both the MM2-cortical-type and MM2-thalamic-type sCJDs could be distinguished,2 we © 2016 Japanese Society of Neuropathology 7 consider that they cannot be distinguished clearly and overlap each other.3 The diagnosis of ‘MM2-cortical + thalamic combined-type’, ‘MM2-thalamic with cortical-type’ or ‘MM2-cortical with thalamic-type’ must be made based on early clinical features and major pathological findings, and not solely on the later, more progressed and widespread involvement of the lesions due to prolonged disease duration.3 In the present case, the pathological findings showed a severely affected inferior olivary nucleus with pseudohypertrophy, and the pathology suggested that the MM2-thalamic-type was complicated. Additionally, the SPECT finding of hypoperfusion of the bilateral thalamus also matched the clinical diagnostic criteria for the MM2thalamic-type.15 Usually, patients with MM2-thalamic-type sCJD clinically show severe insomnia and psychomotor hyperactivity in the early disease stage and neuropathologically show severe involvement of the medial thalamus and the inferior olivary nucleus.1–3,5 Because there were no apparent clinical findings that indicated the MM2thalamic-type, we suggest that the MM2 pathology of the present case be classified as MM2-cortical with thalamictype. Therefore, according to our comprehensive analyses, we diagnosed the present patient with MM1 + MM2-cortical with thalamic-type sCJD. In general, MM1 + 2-type sCJD cases show a combination of MM1-type and MM2-cortical-type pathology.11 To our knowledge, there is no report of MM1 + MM2-cortical-type sCJD with thalamic-type sCJD pathology. We believe that the findings from the present case will allow many new suggestions and speculations about CJD pathogenesis. ACKNOWLEDGMENTS The authors thank Associate Professor Katsuya Sato (Department of Molecular Microbiology and Immunology, Nagasaki University) for his technical analysis of CSF and Clinical Laboratory Technician Masamitsu Nagaoka (Department of Pathology, Oyamada Memorial Spa Hospital) for his technical assistance in the autopsy. This work was supported by a grant-in-aid from the Research Committee of Prion Disease and Slow Virus Infection, the Ministry of Health, Labour and Welfare of Japan, and Grants-in-Aid for Scientific Research Grant Number H27-15 K08369. DISCLOSURE There are no conflicts of interest to declare. REFERENCES 1. Gambetti P, Kong Q, Zou W, Parchi P, Chen SG. Sporadic and familial CJD: classification and characterization. Br Med Bull 2003; 66: 213–239. 8 Iwasaki Y et al. 2. Parchi P, Giese A, Capellari S et al. Classification of sporadic Creutzfeldt-Jakob disease based on molecular and phenotypic analysis of 300 subjects. Ann Neurol 1999; 46: 224–233. 3. Saito Y, Iwasaki Y, Aiba I, Kitamoto T, Yoshida M, Hashizume Y. An autopsy case of MM2-cortical + thalamic-type sporadic Creutzfeldt-Jakob disease. Neuropathology 2011; 31: 523–530. 4. Hoshino A, Iwasaki Y, Izumi M et al. MM1-type sporadic Creutzfeldt-Jakob disease with unusually prolonged disease duration presenting with panencephalopathictype pathology. Neuropathology 2008; 28: 326–332. 5. Hirose K, Iwasaki Y, Izumi M et al. MM2-thalamic-type sporadic Creutzfeldt-Jakob disease with widespread neocortical pathology. Acta Neuropathol 2006; 112: 503–511. 6. Iwasaki Y, Yoshida M, Hashizume Y, Kitamoto T, Sobue G. Clinicopathologic characteristics of sporadic Japanese Creutzfeldt-Jakob disease classified according to prion protein gene polymorphism and prion protein type. Acta Neuropathol 2006; 112: 561–571. 7. Iwasaki Y, Mimuro M, Yoshida M, Sobue G, Hashizume Y. Clinical diagnosis of Creutzfeldt–Jakob disease: accuracy based on analysis of autopsyconfirmed cases. J Neurol Sci 2009; 277: 119–123. 8. Kitamoto T, Shin RW, Doh-ura K et al. Abnormal isoform of prion proteins accumulates in the synaptic structures of the central nervous system in patients with Creutzfeldt-Jakob disease. Am J Pathol 1992; 140: 1285–1294. 9. Kobayashi A, Sakuma N, Matsuura Y, Mohri S, Aguzzi A, Kitamoto T. Experimental verification of a traceback phenomenon in prion infection. J Virol 2010; 84: 3230–3238. 10. Hamaguchi T, Kitamoto T, Sato T et al. Clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease. Neurology 2005; 64: 643–648. 11. Parchi P, de Boni L, Saverioni D et al. Consensus classification of human prion disease histotypes allows reliable identification of molecular subtypes: an inter-rater study among surveillance centres in Europe and USA. Acta Neuropathol 2012; 124: 517–529. 12. Kobayashi A, Mizukoshi K, Iwasaki Y, Miyata H, Yoshida Y, Kitamoto T. Co-occurrence of types 1 and 2 PrP(res) in sporadic Creutzfeldt-Jakob disease MM1. Am J Pathol 2011; 178: 1309–1315. 13. Iwasaki Y, Tatsumi S, Mimuro M, Kitamoto T, Hashizume Y, Yoshida M. Relation between clinical findings and progression of cerebral cortical pathology in MM1-type sporadic Creutzfeldt-Jakob disease: proposed staging of cerebral cortical pathology. J Neurol Sci 2014; 341: 97–104. 14. Satoh K, Nakaoke R, Nishiura Y et al. Early detection of sporadic CJD by diffusion-weighted MRI before the onset of symptoms. J Neurol Neurosurg Psychiatry 2011; 82: 942–943. 15. Terasawa Y, Fujita K, Izumi Y, Kaji R. Early detection of familial Creutzfeldt-Jakob disease on diffusionweighted imaging before symptom onset. J Neurol Sci 2012; 319: 130–132. © 2016 Japanese Society of Neuropathology