Hidradenitis suppurativa: a disease of the absent sebaceous gland? Sebaceous gland number and volume are significantly reduced in uninvolved hair follicles from patients with hidradenitis suppurativa

P>Background The origin of the distribution of segmental vitiligo (SV) has not yet been clearly elucidated. Segmental configurations of cutaneous disorders have been explained using two main interpretations, i.e. following either dermatomal or blaschkolinear distributions. However, facial SV does not always correspond to either of these distributions. Objectives We classified facial SV into several distinctive subtypes according to specific distributions based on long-term observations. Methods In total, 257 patients with facial SV were included, all of whom were closely observed for more than 1 year. The distribution patterns of facial SV were classified according to morphological similarities based on clinical observations. Results The lesions of facial SV were categorized into six subtypes: types I-a and I-b, and types II-V. Type I-a and type IV broadly involved the mid-level face from the forehead to the lower cheek, but type IV lesions selectively appeared on the right side of the face and did not cross the midline. Type I-b lesions chiefly involved the forehead and scalp hair. Types II and III involved the lower face and, frequently, the neck area, and type V lesions were distributed mostly around the right orbital area. The most frequent type of lesion in this study was type I-a (28 center dot 8%), followed by types II (16 center dot 0%), III (14 center dot 4%), IV (10 center dot 9%), I-b (10 center dot 5%) and V (8 center dot 6%). Conclusions Newly established patterns of facial SV may be valuable for certain aspects of prognosis, such as the likely degree and path of lesion spreading.