01-07-2011 | Consensus Letter
A harmonized classification system for FTLD-TDP pathology
Published in: Acta Neuropathologica | Issue 1/2011
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In 2006, two papers were published, each describing pathological heterogeneity in cases of frontotemporal lobar degeneration (FTLD) with ubiquitin-positive, tau-negative inclusions (FTLD-U) [7, 11]. In both studies, large series of cases were evaluated and the investigators felt that they could recognize three distinct histological patterns, based on the morphology and anatomical distribution of ubiquitin immunoreactive neuronal inclusions. The findings of Sampathu et al. were further supported by differential labelling of the pathology, using a panel of novel monoclonal antibodies; whereas, Mackenzie et al. found relatively specific clinicopathological correlations. Most importantly, the pathological features that defined the subtypes in these two studies were almost identical, providing powerful validation of the results. However, because the studies were conducted simultaneously and independently, the numbering of the subtypes, used in the respective papers, did not match (Table 1).
Table 1
Proposed new classification system for FTLD-TDP pathology, compared with existing systems
New system
|
Mackenzie et al. [7]
|
Sampathu et al. [11]
|
Cortical pathology
|
Common phenotype
|
Associated genetic defects
|
---|---|---|---|---|---|
Type A
|
Type 1
|
Type 3
|
Many NCI
|
bvFTD
|
GRN mutations
|
Many short DN
|
PNFA
|
||||
Predominantly layer 2
|
|||||
Type B
|
Type 3
|
Type 2
|
Moderate NCI
|
bvFTD
|
Linkage to chromosome 9p
|
MND with FTD
|
|||||
Few DN
|
|||||
All layers
|
|||||
Type C
|
Type 2
|
Type 1
|
Many long DN
|
SD
|
|
bvFTD
|
|||||
Few NCI
|
|||||
Predominantly layer 2
|
|||||
Type D
|
Type 4a
|
Type 4a
|
Many short DN
|
Familial IBMPFD
|
VCP mutations
|
Many lentiform NII
|
|||||
Few NCI
|
|||||
All layers
|