Transactive response DNA-binding protein 43 (TDP-43) pathological inclusions are found in frontotemporal lobar degeneration (FTLD-TDP) and Alzheimer\'s disease (AD-TDP). While clinically different, TDP-43 inclusions in FTLD-TDP and AD can have similar morphological characteristics. However, TDP-43 colocalizing with tau and forming \"apple-bite\" or \"flame-shaped\" neuronal cytoplasmic inclusions (NCI) are only found in AD-TDP. Here, we describe a case with AD and neuritic plaque-associated TDP-43. The patient was a 96-year-old right-handed Caucasian woman who had developed a slowly progressive amnestic syndrome compatible with typical AD at age 80. Genetic testing revealed APOE ε3/ε4, GRN r5848 CT, and MAPT H1/H2 genotype. Consistent with the old age at onset and long disease duration, limbic-predominant AD was found at autopsy, with high hippocampal yet low cortical neurofibrillary tangle (NFT) counts. Hippocampal and amygdala sclerosis were present. Immunohistochemistry for phospho-TDP-43 showed NCIs, dystrophic neurites, and rare neuronal intranuclear inclusions consistent with FTLD-TDP type A, as well as tau NFT-associated TDP-43 inclusions. These were frequent in the amygdala, entorhinal cortex, hippocampus, occipitotemporal gyrus, and inferior temporal gyrus but sparse in the mid-frontal cortex. Additionally, there were TDP-43-immunoreactive inclusions forming plaque-like structures in the molecular layer of the dentate fascia of the hippocampus. The presence of neuritic plaques in the same region was confirmed using thioflavin-S fluorescent microscopy and immunohistochemistry for phospho-tau. Double labeling immunofluorescence showed colocalization of TDP-43 and tau within neuritic plaques. Other pathologies included mild Lewy body pathology predominantly affecting the amygdala and olfactory bulb, aging-related tau astrogliopathy, and mixed small vessel disease (arteriolosclerosis and amyloid angiopathy) with several cortical microinfarcts. In conclusion, we have identified TDP-43 colocalizing with tau in neuritic plaques in AD, which expands the association of TDP-43 and tau in AD beyond NFTs. The clinical correlate of this plaque-associated TDP-43 appears to be a slowly progressive amnestic syndrome.

BACKGROUND: Age-related macular degeneration (AMD) is a common retinal degenerative disorder among older individuals. Amyloid deposits, a hallmark of cerebral amyloid angiopathy (CAA), may be involved in the pathogenesis of AMD. Since amyloid deposits may contribute to the development of both AMD and CAA, we hypothesized that patients with AMD have a higher prevalence of CAA.
OBJECTIVE: To compare the prevalence of CAA in patients with or without AMD matched for age.
METHODS: We conducted a cross-sectional, 1:1 age-matched, case-control study of patients ≥40 years of age at the Mayo Clinic who had undergone both retinal optical coherence tomography and brain MRI from 2011 to 2015. Primary dependent variables were probable CAA, superficial siderosis, and lobar and deep cerebral microbleeds (CMBs). The relationship between AMD and CAA was assessed using multivariable logistic regression and was compared across AMD severity (none vs early vs late AMD).
RESULTS: Our analysis included 256 age-matched pairs (AMD 126, no AMD 130). Of those with AMD, 79 (30.9%) had early AMD and 47 (19.4%) had late AMD. The mean age was 75±9 years, and there was no significant difference in vascular risk factors between groups. Patients with AMD had a higher prevalence of CAA (16.7% vs 10.0%, p=0.116) and superficial siderosis (15.1% vs 6.2%, p=0.020), but not deep CMB (5.2% vs 6.2%, p=0.426), compared to those without AMD. After adjusting for covariates, having late AMD was associated with increased odds of CAA (OR 2.83, 95% CI 1.10-7.27, p=0.031) and superficial siderosis (OR 3.40, 95%CI 1.20-9.65, p=0.022), but not deep CMB (OR 0.7, 95%CI 0.14-3.51, p=0.669).
CONCLUSIONS: AMD was associated with CAA and superficial siderosis but not deep CMB, consistent with the hypothesis that amyloid deposits play a role in the development of AMD. Prospective studies are needed to determine if features of AMD may serve as biomarkers for the early diagnosis of CAA.

BACKGROUND: Amyloidosis is a very heterogeneous disease. Correct diagnosis is extremely important because of the various treatment options for different types of amyloidosis. This study presents a case report and literature review of the misdiagnosis of fibrinogen Aα-chain amyloidosis (AFib amyloidosis).
METHODS: We report a 65-year-old man diagnosed with proteinuria in 2009. The kidney biopsy revealed the presence of Congo red-stained amyloid deposits. During differential diagnosis, amyloid deposits were discovered in adipose tissue and gingiva. Bone marrow trephine biopsy showed a predominance of lambda chains presenting plasmocytes. Based on performed medical examination, light chain amyloidosis was identified. Therefore, the patient received high-dose melphalan and underwent successful autologous peripheral blood stem cell transplantation. However, proteinuria, worsening of the kidneys\' function, and incorrect levels of free light chains were still observed. In 2019, due to continuous treatment failure, a previously acquired kidney biopsy was examined by mass spectrometry, and numerous fibrinogen deposits were identified. Recommended DNA analysis revealed that the patient had AFib amyloidosis. Therefore, chemotherapy treatment was abandoned, and successful kidney transplantation was performed.
CONCLUSIONS: Today, it is essential for medical practitioners to remember the possibility of rare and hereditary types of amyloidosis. There are multiple cases where a diagnosis was wrong or delayed because of the atypical course of the disease, the coexistence of another disease, and the rarity of AFib amyloidosis, and all of these reasons may result in the wrong treatment that will delay the right therapy. However, with the new, more precise diagnostics methods, such situations will become rare.

BACKGROUND: Porokeratosis ptychotropica represents an unusual form of porokeratosis characterized by symmetrical dyskeratotic skin lesions on the gluteal clefts. Herein, we report a case of porokeratosis ptychotropica.
METHODS: A 33-year-old man, who complained of itching papules and plaques in the gluteal cleft and the buttocks for the last 7 years. Clinical examination showed a large well-defined reddish brown verrucous plaque located on both buttocks along with satellite papules on the inner thigh. Dermoscopy and histopathological findings were consistent with porokeratosis.
METHODS: He was diagnosed with porokeratosis ptychotropica.
RESULTS: No significant improvement was observed following treatment with oral acitretin and a topical retinoid.
CONCLUSIONS: The case report highlights the need for awareness amongst dermatologists for porokeratosis ptychotropica as a differential diagnosis for pruritic papules in the gluteal fold.

Quantification of in vivo amyloid and tau PET imaging relationships with postmortem measurements are critical for validating the sensitivity and specificity imaging biomarkers across clinical phenotypes with Alzheimer disease neuropathologic change (ADNC). This study examined the quantitative relationship between regional binding of in vivo 18F-florbetapir amyloid PET and 18F-flortaucipir tau PET with postmortem stereological counts of amyloid plaques and neurofibrillary tangles (NFT) in a case of primary progressive aphasia (PPA) with ADNC, where neurodegeneration asymmetrically targets the left hemisphere. Beginning 2 years prior to death, a 63-year-old right-handed man presenting with agrammatic variant PPA underwent a florbetapir and flortaucpir PET scan, and neuropsychological assessments and magnetic resonance imaging sessions every 6 months. Florbetapir and flortaucpir PET standard uptake value ratios (SUVRs) were quantified from 8 left and right hemisphere brain regions with stereological quantification of amyloid plaques and NFTs from corresponding postmortem sections. Pearson\'s correlations and measures of asymmetry were used to examine relationships between imaging and autopsy measurements. The three visits prior to death revealed decline of language measures, with marked progression of atrophy. Florbetapir PET presented with an atypical focal pattern of uptake and showed a significant positive correlation with postmortem amyloid plaque density across the 8 regions (r = 0.92; p = 0.001). Flortaucipir PET had a left-lateralized distribution and showed a significant positive correlation with NFT density (r = 0.78; p = 0.023). Flortaucipir PET and NFT density indicated a medial temporal lobe sparing presentation of ADNC, demonstrating that AD does not always target the medial temporal lobe. This study adds additional evidence, in a non-amnestic phenotype of ADNC, that there is a strong correlation between AD PET biomarkers, florbetapir and flortaucipir, with quantitative neuropathology. The atypical and focal presentation of plaque density and florbetapir PET uptake suggests not all amyloid pathology presents as diffuse across neocortex.

Gerstmann-Sträussler-Scheinker disease (GSS) is a rare neurodegenerative illness that belongs to the group of hereditary or familial Transmissible Spongiform Encephalopathies (TSE). Due to the presence of different pathogenic alterations in the prion protein (PrP) coding gene, it shows an enhanced proneness to misfolding into its pathogenic isoform, leading to prion formation and propagation. This aberrantly folded protein is able to induce its conformation to the native counterparts forming amyloid fibrils and plaques partially resistant to protease degradation and showing neurotoxic properties. PrP with A117V pathogenic variant is the second most common genetic alteration leading to GSS and despite common phenotypic and neuropathological traits can be defined for each specific variant, strikingly heterogeneous manifestations have been reported for inter-familial cases bearing the same pathogenic variant or even within the same family. Given the scarcity of cases and their clinical, neuropathological, and biochemical variability, it is important to characterize thoroughly each reported case to establish potential correlations between clinical, neuropathological and biochemical hallmarks that could help to define disease subtypes. With that purpose in mind, this manuscript aims to provide a detailed report of the first Spanish GSS case associated with A117V variant including clinical, genetic, neuropathological and biochemical data, which could help define in the future potential disease subtypes and thus, explain the high heterogeneity observed in patients suffering from these maladies.

The authors present a case of fatal amyloid cardiomyopathy, which was diagnosed only upon autopsy. A 57-year-old man was admitted to the hospital for scheduled percutaneous cardiac procedure of transcatheter radiofrequency ablation due to persistent atrial fibrillation and atrial flutter. Ventricular fibrillation was recorded in the monitor 2 h after the surgical procedure. Therefore, he was defibrillated and intubated, but he died for nosocomial pneumonia 26 days after being admitted. A judicial autopsy was ordered by the prosecutor due to an alleged medical malpractice. The autopsy confirmed the cause of death being pneumonia, but also revealed an occult restrictive cardiomyopathy with a thick and firm myocardium. Viscera samples were then collected for microscopic examination. Histopathologic analysis showed diffuse amyloid deposits in the myocardium, especially in the perivascular and subendocardial spaces. Amyloid deposits were also detected in all the other organs, except for the brain. Furthermore, immunohistochemistry for light chains was performed on the heart tissue sample, resulting to be positive. In the case presented herein, autopsy and histopathologic examination were crucial to diagnose an occult systemic amyloidosis (AL-type). In fact, it has been observed that the rarity of systematic amyloidosis and its unusual clinical onset were at first mistakenly perceived as a medical malpractice due to a technical error within the catheter ablation for atrial fibrillation. As a consequence, upon discussing the clinical and medicolegal implications concerning the case, the focus was placed on the undiagnosed systemic amyloidosis and on the causality between surgical procedure and the patient\'s death.

An 80-year-old man with dementia demonstrated cerebellar hemorrhage. Autopsy revealed pathology compatible with Alzheimer\'s disease and cerebral amyloid angiopathy (CAA). CAA was more prevalent in the occipital lobe than in the frontal, parietal, and temporal lobes; however, amyloid-β (Aβ)-containing senile plaques were less abundant in the occipital cortex than in the other cortices. In the cerebellum, abundant CAA-involved vessels were observed in the subarachnoid space and molecular layer and to a lesser extent in the Purkinje and granule layers. On consecutive sections, Aβ1-42 immunohistochemistry revealed senile plaques and CAA-involved vessels with strong immunoreactivity whereas Aβ1-40 immunohistochemistry identfied CAA-involved vessels with strong immunoreactivity and senile plaques with weak immunoreactivity in the cerebellar cortices.

Alzheimer disease (AD) is the most common cause of dementia in older individuals (>65 years) and has a long presymptomatic phase. Preventive therapies for AD are not yet available, and potential disease-modifying therapies targeting amyloid-β plaques in symptomatic stages of AD have only just been approved in the United States. Small-molecule inhibitors of β-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1; also known as β-secretase 1) reduce the production of amyloid-β peptide and are among the most advanced drug candidates for AD. However, to date all phase II and phase III clinical trials of BACE inhibitors were either concluded without benefit or discontinued owing to futility or the occurrence of adverse effects. Adverse effects included early, mild cognitive impairment that was associated with all but one inhibitor; preliminary results suggest that the cognitive effects are non-progressive and reversible. These discontinuations have raised questions regarding the suitability of BACE1 as a drug target for AD. In this Perspective, we discuss the status of BACE inhibitors and suggest ways in which the results of the discontinued trials can inform the development of future clinical trials of BACE inhibitors and related secretase modulators as preventative therapies. We also propose a series of experiments that should be performed to inform \'go-no-go\' decisions in future trials with BACE inhibitors and consider the possibility that low levels of BACE1 inhibition could avoid adverse effects while achieving efficacy for AD prevention.

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