Objective: Objective:

Describe the results of skin biopsy for phosphorylated alpha-synuclein (P-SYN) and dopamine transporter (DAT) imaging in patients previously diagnosed with psychogenic parkinsonism (PP) and evaluate the diagnostic utility of P-SYN biopsy in identifying underlying organic disease.

Background: Background:

PP remains poorly characterized due to its clinical overlap with idiopathic Parkinson’s disease (PD) and the frequent coexistence of both in up to 30% of cases. Even with advanced diagnostic modalities differentiation remains challenging. P-SYN can be detected through commercially available P-SYN skin biopsy, which helps identify symptomatic or prodromal synucleinopathies, including PD, multiple system atrophy, dementia with Lewy bodies, pure autonomic failure, and REM sleep behavior disorder. DAT imaging is often used to help differentiate between PD and PP, though it has pitfalls including false negatives, inaccurate results due to intake of psychiatric medications and subjective visual interpretation. To our knowledge, there are no published studies investigating results of cutaneous P-SYN in patients with PP.

Method: Design/Methods:

We retrospectively reviewed charts of patients diagnosed with PP who underwent DAT imaging, and P-SYN skin biopsy from 2019–2025 at our facility.

Results: Results:

Ten patients with PP were identified (7 men, 3 women; mean age 58.8 ± 16.55 years). DAT imaging was abnormal in 3/10 (30%) and normal in 7/10 (70%). P-SYN biopsy was (+) in 5/10 (50%). P-SYN positivity localized to the posterior cervical region in 4/5 (80%) and the distal leg in 1/5 (20%). Of the 7 patients with normal DAT scans, 3/7 (42.85%) were P-SYN(+). Of the 3 patients with abnormal DAT scans, 2/3 (66.66%) was P-SYN(+).

Conclusion: Conclusions:

P-SYN skin biopsy may identify underlying synucleinopathy in patients initially diagnosed as PP, particularly when DAT imaging is normal. Incorporation of P-SYN biopsy into standard evaluation protocols may improve diagnostic accuracy of PP and identify those with concurrent synucleinopathy to guide appropriate management.

Limitations:

Small sample size and referral bias limit generalizability. Additional barriers such as procedural discomfort, travel constraints, and testing costs may have influenced performance of skin biopsy.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/skin-biopsy-for-phosphorylated-alpha-synuclein-and-dat-imaging-in-patients-diagnosed-with-psychogenic-parkinsonism/