Scarring versus Non-Scarring Alopecia: An Interobserver Histopathological Reproducibility Study.

Introduction: Distinguishing scarring (SA) versus non-scarring alopecia (NSA) may not be a simple procedure on either clinical or histopathological views. Aims: We sought to study the interobserver variability in the histopathological assessment of SA versus NSA, including clinical-pathological considerations. Methods: Two dermatopathologists independently interpreted the same set of 100 specimens (89 patients). The samples were serial sectioned and stained by hematoxylin and eosin and Verhöeff methods. The patients' mean age was 46 years, with 13 being males and 76 females. Results: In 16/100 samples, there was no consensus among the two examiners regarding SA versus NSA (weighted kappa = 0.6583; 95% CI); 3/16 patients were re-biopsied, and in the second sample, consensus was reached. In 76/89 patients, the anatomopathological examination was helpful in defining the SA versus NSA subtype. Of the 84 samples in which there was interobserver agreement, 4 which had been considered scarring in the routine pathological report were re-classified as non-scarring, whereas one biopsy, previously diagnosed as non-scarring, was now considered cicatricial due to the newly found areas of lichenoid inflammation in the infundibular epithelium. Discussion: The ideal scalp examination may require deep serial biopsy sectioning, elastic tissue stain, re-biopsy, and strict clinical-evolutive correlation.