The homogeneity of hidradenitis suppurativa lesions. A histological study of intra-individual variation.

Recent data suggest that hidradenitis suppurative is a disease of the follicle, but the histological homogeneity of findings over time and in different anatomical regions has not been verified. Its description may help towards a better classification of the follicular diseases. Correct classification provides both knowledge by interference and a way of generalizing with respect to the significance of specific findings. The intra-individual variation of hidradenitis was described through classification of specimens taken from patients with multiple simultaneous or consecutive excisions. A total of 51 specimens from 11 patients were examined; of these 30 were from synchronous biopsies, and 21 from consecutive biopsies (range 2 months to 6 years). The majority of specimens (44/51) contained poral occlusion, sinus tracts or cysts. This pattern was present in 50-85% of the specimens from any given patient with hidradenitis. No primary apocrine involvement was seen. Fibrosis occurred often (33/51 specimens), and eccrine involvement was seen more often than apocrine involvement (10 vs 7 specimens). The homogeneous histology of hidradenitis supports its reclassification as a follicular disease. The reproducibility of the findings further suggests that the changes are specific and that hidradenitis is therefore a definite disease entity within the spectrum of follicular diseases. Additional functional studies may help classify hidradenitis more precisely in relation to other follicular diseases.