Combined Diagnostic Approach Improves Accuracy in Differentiating Eczema From Psoriasis

A new study suggests that combining traditional dermatopathology with molecular testing may significantly improve diagnostic accuracy for eczema and psoriasis, offering clinicians a more reliable approach to guiding treatment decisions for 2 of the most common inflammatory skin diseases.¹

Eczema and psoriasis often appear similar clinically,² with up to 15% of psoriasis cases initially diagnosed as eczema, though the conditions have different underlying mechanisms that require distinct treatments. Diagnosis typically relies on clinical evaluation and dermatopathology, yet overlapping or subtle features, particularly in early or ambiguous cases, can make accurate differentiation challenging.¹ As a result, misdiagnosis can lead to ineffective treatment, prolonged symptoms, and increased health care costs.

To address these limitations, researchers evaluated the diagnostic performance of dermatopathology alongside polymerase chain reaction (PCR)–based molecular testing. They published their findings in the Journal of the European Academy of Dermatology and Venereology.

The analysis included 73 skin biopsy samples from patients with suspected eczema or psoriasis. Each sample underwent independent assessment using conventional dermatopathology from 14 independent dermapathologists and PCR-based testing designed to detect gene expression patterns associated with each condition. These molecular signatures reflect underlying immune pathways that differ between eczema and psoriasis, providing an additional layer of diagnostic information beyond visual tissue assessment.

Findings from the study showed that while dermatopathology alone demonstrated strong diagnostic performance (76.9% accuracy, 70% sensitivity, 81.6% specificity), discrepancies remained in a subset of cases.

“Agreement was particularly low in diagnostically ambiguous cases, underscoring the limitations of morphology-based evaluation when inflammatory patterns overlap or remain subtle,” explained the researchers. “This aligns with prior studies in other diagnostic fields, including melanocytic tumors, where almost 50% interrater variability persists even among experts.”

In these new findings, PCR testing provided valuable clarification for the ambiguous instances, helping to resolve cases where histologic findings were inconclusive or conflicting.

When the 2 methods were combined, diagnostic concordance improved significantly compared with either approach used independently. The integrated strategy allowed for more precise classification of disease, particularly in cases where traditional histologic criteria alone might lead to uncertainty or misclassification.

The study also highlighted the complementary nature of the approaches. Dermatopathology offers detailed structural insights into skin architecture, while PCR-based testing captures molecular activity at the level of gene expression. Together, these methods provide a more comprehensive understanding of disease biology, enabling clinicians to move beyond surface-level assessment toward more precise diagnosis, described the researchers.

This has important implications for patient care, noted the group. Treatment options for eczema and psoriasis differ substantially, particularly with the growing use of targeted biologic therapies that act on specific immune pathways. Accurate diagnosis is essential to ensure that patients receive the most appropriate therapy and avoid unnecessary exposure to ineffective or potentially harmful treatments.

The researchers also detailed how in addition to improving diagnostic accuracy, the combined approach may help reduce diagnostic delays. Patients with unclear or evolving symptoms often require multiple consultations and repeat biopsies before a definitive diagnosis is reached. Incorporating molecular testing earlier in the diagnostic process could streamline care and shorten the time to appropriate treatment.

However, several challenges remain before widespread implementation. PCR-based testing requires specialized laboratory capabilities and may not yet be available in all clinical settings. Cost considerations and standardization of testing protocols will also need to be addressed to ensure consistent and equitable access.

The authors suggested that future research should focus on validating these findings in larger and more diverse patient populations, as well as exploring how molecular diagnostics can be integrated into routine clinical workflows.

References

1. Schmitt A, Proksch S, Gutzweilerr L, et al. Diagnostic concordance of dermatopathology and PCR in differentiating eczema from psoriasis. J Eur Acad Dermatol Venereol. Published online March 12, 2026. doi:10.1111/jdv.70388

2. Is it psoriasis or eczema? National Psoriasis Foundation. Updated October 6, 2025. Accessed March 19, 2026. https://www.psoriasis.org/advance/psoriasis-or-eczema-atopic-dermatitis/