A 50-year-old man presents with progressive memory loss, personality changes, and language difficulties over 3 years. MRI shows severe bilateral temporal lobe atrophy, particularly involving the hippocampus and parahippocampal gyrus. Autopsy reveals Pick bodies, which are argyrophilic neuronal cytoplasmic inclusions. The protein predominantly composing Pick bodies is:
- A Alpha-synuclein
- B Tau (3-repeat isoform) ✓
- C TDP-43
- D Beta-amyloid
Correct answer: B. Tau (3-repeat isoform)
Explanation
Pick disease (a subtype of frontotemporal dementia) is characterized by Pick bodies, which are round argyrophilic neuronal cytoplasmic inclusions composed predominantly of hyperphosphorylated tau protein, specifically the 3-repeat (3R) tau isoform. Alpha-synuclein composes Lewy bodies in Parkinson disease and Lewy body dementia. TDP-43 is found in most cases of ALS and a subset of frontotemporal dementia (FTLD-TDP). Beta-amyloid forms senile plaques in Alzheimer disease.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.