Psoriasis is a chronic inflammatory skin disease, and noninvasive diagnostic tools are essential for accurate diagnosis and treatment monitoring. Multiphoton microscopy (MPM) enables real-time, noninvasive skin imaging with submicron resolution. This study evaluated the diagnostic accuracy of MPM in psoriasis and its potential application in therapeutic monitoring. This prospective observational study enrolled 34 patients with psoriasis. It comprised three parts: (1) analysis of imaging features of lesional and nonlesional skin using multiphoton microscopy (MPM; Transcend Vivoscope); (2) evaluation of the diagnostic performance of MPM parameters compared with reflectance confocal microscopy (RCM); and (3) prospective monitoring of 24 patients treated with Benvitimod (Tapinarof) cream for 8 weeks (T0/T1/T2). MPM detected psoriasis characteristics (including hyperkeratosis, parakeratosis, an absent stratum granulosum, enlarged nucleus diameter, and absent bright rimming) with comparable diagnostic efficiency to RCM (AUC = 0.838, p < 0.001 vs. 0.824, p < 0.001). Psoriatic lesions showed significant perinuclear fluorescence accumulation compared to healthy skin (p < 0.001). All imaging features improved significantly after 8 weeks of treatment (p < 0.001). PASI/TLS scores showed correlations with the epidermal thickness (r = 0.403/0.492, p < 0.001), nuclear diameter (r = 0.4/0.375, p < 0.001), and fluorescence intensity (r = -0.419/-0.492, p < 0.001). MPM is a novel and non-invasive imaging technique for psoriasis evaluation and treatment monitoring.
