Hidradenitis suppurativa or acne inversa. A clinicopathological study of early lesions.

The pathogenesis of hidradenitis suppurativa (HS) has given rise to controversy about whether the central pathogenetic feature is an apocrine follicular occlusion (with subsequent bacterial infection) or it is a folliculitis with secondary involvement of both apocrine and eccrine sweat glands. Most previous concepts have focused on apocrine gland involvement. A prospective study of 27 consecutive patients (39 biopsies) was performed to investigate the immune-histological findings in early, newly formed lesions. Most of them were examined within 3 days of clinical onset. Histopathological findings showed that the initial lesion is an occluding spongiform infundibulo-folliculitis. Furthermore, it was found that T cells predominated in the lymphocytic cell population. A high percentage of HLA-DR positive lymphocytes was found in an inverse relationship with Leu-8 positive lymphocytes. Additionally, a sharp decline in the T-helper/suppressor ratio was observed after the initiation. These results reveal that the primary event in HS is an infundibulofolliculitis with secondary involvement of apocrine glands. Acne inversa would be a more appropriate name.