What question did this study set out to answer?

The research aims to evaluate fibroblast activation in psoriasis patients and its correlation with the risk of developing psoriatic arthritis.

March 25, 2026Open Access

Increased synovial and entheseal fibroblast activation detected by 68 Ga-FAPI-PET/CT is associated with the development of psoriatic arthritis in psoriasis patients with arthralgia

Key Points

The research aims to evaluate fibroblast activation in psoriasis patients and its correlation with the risk of developing psoriatic arthritis.
Psoriasis patients with joint pain underwent 68 Ga-FAPI-PET/CT imaging.
Fibroblast activation was identified at 71 articular sites with specific criteria.
Clinical and ultrasound findings were analyzed for associations.
Survival analyses were performed to assess the risk of progression to psoriatic arthritis.
82% of evaluated patients were positive for fibroblast activation.
FAPI-positive patients had significantly higher body mass index and disease activity scores.
Fibroblast activation frequently occurred in large joints and was associated with low-grade synovial hyperplasia and concomitant osteoarthritis.
FAPI-positive patients had a sevenfold increased risk of progressing to psoriatic arthritis compared to FAPI-negative patients.

Abstract

Objectives To assess the clinical and imaging characteristics associated with fibroblast activation detected by 68 Gallium-labelled fibroblast activation protein inhibitor positron emission tomography/CT ( 68 Ga-FAPI-PET/CT) in patients with psoriasis and whether 68 Ga-FAPI uptake correlates with the risk of progression to psoriatic arthritis (PsA). Methods Psoriasis patients with arthralgia underwent 68 Ga-FAPI-PET/CT and were followed up prospectively. 68 Ga-FAPI uptake was assessed at 71 articular sites and patients with ≥1 joint with 68 Ga-FAPI uptake and PET/CT Joint Index≥2 were considered FAPI positive. The associations between FAPI uptake and clinical and ultrasound (US) findings were investigated. Survival analyses were conducted to assess the association between 68 Ga-FAPI uptake and progression to PsA. Results 45 patients with psoriasis were enrolled, 37 of whom (82%) were FAPI positive. FAPI-positive psoriasis patients had significantly higher body mass index (BMI) (p=0.036) and Disease Activity Score 28-C reactive protein (p=0.033) compared with FAPI-negative patients. 68 Ga-FAPI uptake was most frequent in large joints and mechanically stressed sites and was more likely in the presence of low-grade synovial hyperplasia (OR: 1.77, 95% CI 1.08 to 2.89), entheseal Power Doppler (OR: 3.80, 95% CI 1.66 to 8.72) and concomitant osteoarthritis (OA). FAPI-positive patients showed a higher risk of progression to PsA compared with FAPI-negative patients (HR 7.1, 95% CI 0.9 to 53.6) (log-rank p=0.028). Only 1/8 patients with psoriasis (12.5%) without 68 Ga-FAPI uptake developed PsA, as opposed to 18/37 (49%) of FAPI-positive patients. Conclusions In psoriasis patients with arthralgia, 68 Ga-FAPI uptake, indicating fibroblast activation, is associated with higher BMI, more pain, subclinical US changes and concomitant OA. Pathological 68 Ga-FAPI uptake at articular sites was indicative of higher risk of progression to PsA in our cohort, suggesting fibroblast activation as a crucial step to develop PsA.

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