TY - JOUR

T1 - Clinical, microbiological, immunological and imaging characteristics of tunnels and fistulas in hidradenitis suppurativa and Crohn's disease

AU - Jorgensen, Astrid-Helene Ravn

AU - Thomsen, Simon Francis

AU - Karmisholt, Katrine Elisabeth

AU - Ring, Hans Christian

PY - 2020

Y1 - 2020

N2 - Hidradenitis suppurativa (HS) tunnels and Crohn's disease (CD) fistulas are a challenge to treat. Although pathogenic similarities have been described between HS and CD, recent studies indicate that clinical, microbiological, immunological and imaging characteristics differ between these diseases. This review highlights the differences between HS tunnels and CD fistulas. Next-generation sequencing studies demonstrate a microbiome in HS tunnels dominated by Porphyromonas spp., Prevotella spp. whereas no specific bacteria have been associated with cutaneous CD. Immunologically, TNF has been found upregulated in HS tunnels along with various interleukins (IL-8, IL-16, IL-1 alpha and IL-1 beta). In CD fistulas, Th1, Th17, IL-17, IFN-, TNF and IL-23 are increased. US imaging is an important tool in HS. US of HS tunnels depict hypoechoic band-like structure across skin layers in the dermis and/or hypodermis connected to the base of a widened hair follicle. In CD, MR imaging of simple perianal fistulas illustrates a linear, non-branching inflammatory tract relating to an internal opening in the anus or low rectum and an external opening to the skin surface. An increased awareness of the immediate potential differences between HS tunnels and CD fistulas may optimize treatment regimens of these intractable skin manifestations.

AB - Hidradenitis suppurativa (HS) tunnels and Crohn's disease (CD) fistulas are a challenge to treat. Although pathogenic similarities have been described between HS and CD, recent studies indicate that clinical, microbiological, immunological and imaging characteristics differ between these diseases. This review highlights the differences between HS tunnels and CD fistulas. Next-generation sequencing studies demonstrate a microbiome in HS tunnels dominated by Porphyromonas spp., Prevotella spp. whereas no specific bacteria have been associated with cutaneous CD. Immunologically, TNF has been found upregulated in HS tunnels along with various interleukins (IL-8, IL-16, IL-1 alpha and IL-1 beta). In CD fistulas, Th1, Th17, IL-17, IFN-, TNF and IL-23 are increased. US imaging is an important tool in HS. US of HS tunnels depict hypoechoic band-like structure across skin layers in the dermis and/or hypodermis connected to the base of a widened hair follicle. In CD, MR imaging of simple perianal fistulas illustrates a linear, non-branching inflammatory tract relating to an internal opening in the anus or low rectum and an external opening to the skin surface. An increased awareness of the immediate potential differences between HS tunnels and CD fistulas may optimize treatment regimens of these intractable skin manifestations.

KW - hidradenitis suppurative

KW - inflammation

KW - inflammatory skin diseases

U2 - 10.1111/exd.14036

DO - 10.1111/exd.14036

M3 - Review

C2 - 31519056

VL - 29

SP - 118

EP - 123

JO - Experimental Dermatology

JF - Experimental Dermatology

SN - 0906-6705

ER -