High-Resolution Ex Vivo Confocal Microscopy to Distinguish Cutaneous T-Cell Lymphoma from Inflammatory Mimickers

Cutaneous T-cell lymphoma (CTCL) often clinically resembles inflammatory dermatoses such as eczema, making accurate and timely diagnosis challenging. Since early differentiation is critical for appropriate treatment and prognosis, fast and reliable diagnostic tools are needed. Ex vivo confocal laser scanning microscopy (EVCM) has emerged as a promising technique for rapid, high-resolution tissue assessment. As CTCL is difficult to identify based on clinical presentation alone and is frequently misdiagnosed as eczema, this study assessed the diagnostic accuracy and clinical utility of EVCM in differentiating CTCL from eczema, as well as interobserver agreement among examiners with varying experience. Fifty specimens (25 eczema, 25 CTCL) were imaged using EVCM (Vivascope 2500 M-G4; Vivascope GmbH, Munich, Germany). Three independent, blinded dermatologists with different experience levels classified lesions based solely on digital H&E-like images. Sensitivity, specificity, and predictive values were calculated. EVCM showed high diagnostic accuracy, with a mean concordance rate of 82.67%. The dermatohistopathologist achieved the highest accuracy (84%), followed by two trained dermatologists (82% each). Sensitivity ranged from 0.80 to 0.88 and specificity from 0.76 to 0.84, with comparable predictive values and almost perfect interobserver agreement (Fleiss' κ = 0.89). Misclassifications mainly involved the same diagnostically challenging cases across both entities. EVCM demonstrated high diagnostic accuracy across examiners of varying experience, supporting its potential as a rapid bedside tool for distinguishing CTCL from eczema. While not replacing histopathology as the gold standard, it may meaningfully complement routine diagnostics. Integration of immunohistochemistry or artificial intelligence could further enhance diagnostic precision.