[1724] Frontotemporal Lobar Degeneration (FTLD): Updated Pathology and Co-Existing Neurodegenerative Phenomena in a Cohort of 52 Patients

Kelvin Au, Sandra Black, Juan Bilbao, Mario Masellis, Julia Keith. Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Background: The pathological classification of FTLD has drastically changed in the past few years with identification of intracellular proteins implicated in the disease. Multiple neurodegenerative phenomena often co-exist at autopsy yet their role in the etiology of FTLD and their impact on clinical phenotype is poorly understood. Our goals were to examine CNS autopsy cases collected over the last 13 years with FTLD, update the pathological classification and document co-existing neurodegenerative phenomena.
Design: The archives at SHSC were searched for autopsy cases since 2000 with a diagnosis of FTLD who were assessed at the SHSC Cognitive Neurology Clinic (N = 52). The FTLD type and subtype were revised according to the recent FTLD classification scheme using the original autopsy slides and immunohistochemistry (IHC) for TDP43, p62, & tau (AT8). Cases were screened for co-existing Alzheimer's pathology (beta-amyloid and tau), Lewy bodies (alpha-synuclein), mesial temporal sclerosis (MTS), argyrophilic grains (tau), co-existing TDP-43 pathology, and cerebrovascular disease.
Results: 44% of our cases required revision to their diagnosis. The most common diagnosis was FTLD-tau (36/52 or 69%, with 16 cases of Progressive Supranuclear palsy, 10 Corticobasal Degeneration, 8 Pick's, and 1 each of Argyrophilic grain disease and Globular Glial Inclusions). 16/52 (31%) were FTLD-TDP (9 Mackenzie type 1, 3 each of Mackenzie type 2 & 3 & 1 c9orf72). Co-existing neurodegenerative phenomena were common in our cohort with less than a third of cases being pure FTLD. The most frequent was MTS (present in 42%, especially older patients and those with FTLD-TDP Mackenzie type 1), while significant Alzheimer's pathology was seen in 26%, Lewy bodies in 19%, and Argyrophilic grains in 13.5%.
Conclusions: The relative frequency of each FTLD pathologic subtype in our cohort is comparable to other autopsy series from dementia clinics, and the 44% of cases requiring re-classification in our series is reflective of the rapidly evolving understanding of these disorders. Our series reports abundant co-existing neurodegenerative phenomena, which have often been overlooked in these patients historically, and our next step is to correlate the co-existing neurodegenerative phenomena with clinical symptomatology to determine whether their presence alters the clinical phenotype of FTLD.
Category: Neuropathology

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 252, Wednesday Afternoon


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