Papulopustular lesions (PPL), the most common type of cutaneous lesions in Behçet's disease (BD), clinically may not be differentiated from ordinary acne. Disagreement exists as to the exact nature of these acneiform and folliculitis-like lesions and whether to include them as a major criterion.
We investigated whether PPL can be a useful tool for the diagnosis of BD when non-follicular lesions over the trunk or extremities were selected, and were correlated with histological and/or immunofluorescence study.
Seventeen patients with BD (five women, 12 men; mean +/- SEM age, 32 +/- 7.9 years), were enrolled in the study with blind histopathological and immunofluorescence studies. Biopsies of the PPL and adjacent (approximately 2 cm distant) normal-appearing skin were performed from the extremities and trunk. Follicle-based acneiform lesions and those lesions over face were excluded. Histological evaluation primarily included epidermal and dermal alterations, cellular infiltration and vascular changes. We also performed direct immunofluorescence studies, using polyclonal antibodies for IgA, IgG, IgM, C3 and fibrin.
Lesional specimens of the patients with BD revealed a significant leucocytoclastic vasculitis as compared with non-lesional skin (P<0.05). The vessels of the lesional skin showed a higher IgM deposition than non-lesional skin (52.9% and 17.6%) (P<0.05). IgG, C3 and fibrin deposits on the vessels of the lesional skin were also higher than non-lesional skin (35.3, 11.8%; 41.2, 17.6%; and 47.1, 17.6%, respectively), but the differences were not statistically significant.
Our findings indicate that non-follicular PPL over the trunk or extremities are more specific, and immune complex-mediated vasculitis is likely to be the main feature of these lesions, as they are in other cutaneous lesions of BD.