Are There Indications for Isotretinoin Treatment of Hidradenitis Suppurativa?

ported in a total of 7 studies of 32 patients, was high (65.6%) [4] . This fits the concept that there are numerous differences between HS and acne, at least in therapy [5, 6] , and in addition, that the term acne inversa (as well as HS) appears to be also a misnomer [6] . A possible explanation for the limited therapeutic response of isotretinoin may be the absence of any significant sebaceous gland involvement of HS [4, 5] . However, there are patients who respond well to isotretinoin [1–4] . What specific group could this be? It is suggested that the acne-prone HS patients should try isotretinoin [1] . It is well known that acne and HS can occur in the same person. This clinical overlap has led to the inclusion of inhomogeneous patients in the treatment groups. It concerns 2 possible different types of HS: firstly, the classical HS patients (typical lesions on typical locations, i.e., axillary and inguinal involvement) and secondly, the classical HS type with acne affecting the face and the back. The latter disease has also been called acne ectopica or acne tetrad. It has been suggested that patients of these 2 types would respond to isotretinoin in a different way [7–9] . The HS response rates to isotretinoin in a total of 7 studies of at least 11 patients (the number of patients in 2 studies was unspecified) with acne and coexisting HS were at best equivocal compared to the excellent results in acne treatment [8, 9] . In the same patients the acne seemed to clear completely or was much improved, while in most case reports the HS lesions remained and showed only limited response. A follow-up period was never mentioned [9] . In addition, in the retrospective