Histopathological and clinical evaluation of papulopustular lesions in Behcet's disease

Objective. Behcet's disease (BD) is a chronic inflammatory disorder characterised by aphthous stomatitis, genital ulcerations, erythema nodosum-like manifestations and papulopustular lesions. While a neutrophilic vasculitis accompanies most skin lesions it is usually regarded that the papulopustular lesions in BD are similar to acne vulgaris (AV). The aim of our current study was to further assess the clinical and histopathological features of papulopustular lesions in BD and how these features compared to those of AV. Methods. To analyse the histopathological features of BD and AV, 89 punch biopsies were taken from 58 BD (52 male, 6 female) and 31 AV patients (26 male, 5 female). Sections were evaluated in a blind manner by two different pathologists. A dermatologist who was blind to the patients' diagnosis counted the number of papules, pustules, comedones, folliculitis, cysts and nodules on the face, chest, back, upper and lower extremities. Results. The number of papules, pustules and comedones was higher on the face in the AV group, whereas in the BD group, both number of papules and folliculitis on the back and that of folliculitis were higher on the lower extremities in the AV group. With the exception of comedone formation, which was more frequent among the AV patients [20131 (64.5%) vs. 23158 (39.6%), p=0.025] the presence of suppurative folliculitis/perifolliculitis, intrafollicular abscess formation, leukocytoclastic vasculitis or microorganisms were not useful in differentiating BD from AV. However the interobserver agreement for histologic assessment was low. Kappa was 0.17 for suppurative foliculitis / perifolliculitis; 0.39 for intrafollicular abscess formation; 0.51 for leukocytoclastic vasculitis. Conclusion. In the BD group, although the inflammatory lesions located on the face were less than those in the AV group inflammatory lesions such as folliculitis on the legs were only seen, again in the BD group. The papulopustular lesions of BD could not be distinguished from AV by histology. Some of this might be due to high interobsever variation in interpretation. Acne is an inherent manifestation of BD.