Introduction

Many inflammatory dermatoses clinically resemble allergic skin diseases.

Aim

This study aimed to characterize the final histopathological diagnoses in patients referred with suspected allergic skin lesions who ultimately did not have a primary allergic pathology.

Material and methods

This single-center, retrospective observational study included 279 adult patients evaluated in an Allergy and Immunology clinic for suspected allergic lesions, who subsequently underwent diagnostic skin biopsy after no primary allergic diagnosis was established. Final biopsy-based diagnoses were classified into 11 major diagnostic categories, and demographic characteristics were compared across groups.

Results

The initial clinical suspicion of “allergy” evolved into a specific non-primary allergic diagnosis in most patients. Eczematous dermatitis was the most frequent diagnostic group (23.7%), followed by papulosquamous diseases (16.1%) and vascular diseases (12.5%). Diagnostic groups more closely associated with allergy, such as urticaria/prurigo (10.8%) and drug reactions (7.5%), were less frequent. A significant gender difference was observed (p = 0.001), with females predominating particularly in urticaria/prurigo and vascular diseases.

Conclusions

In patients with persistent diagnostic uncertainty following two-stage specialist evaluation, skin biopsy frequently reveals non-allergic dermatoses. Early utilization of biopsy may enhance diagnostic accuracy and prevent prolonged misclassification of “allergy mimics.”