Hidradenitis suppurativa is a severe and debilitating dermatologic disease. Clinical management is challenging and consists of both medical and surgical approaches, which must often be combined for best outcomes. Therapeutic approaches have evolved rapidly in the last decade and include the use of

Hidradenitis suppurativa is a chronic inflammatory disorder affecting hair follicles, with profoundly negative impact on patient quality of life. Evidence informing ideal evaluation and management of patients with hidradenitis suppurativa is still sparse in many areas, but it has grown substantially in the last decade. Part I of this evidence-based guideline is presented to support health care practitioners as they select optimal management strategies, including diagnostic testing, comorbidity screening, and both complementary and procedural treatment options. Recommendations and evidence grading based on the evidence available at the time of the review are provided.

Background: A needs assessment for patients with hidradenitis suppurativa (HS) will support advancements in multidisciplinary care, treatment, research, advocacy, and philanthropy.

Objective To understand whether directly-measured psoriasis severity is associated with vascular inflammation assessed by 18F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET/CT). Approach In depth cardiovascular and metabolic phenotyping was performed in adult psoriasis patients (n=60) and controls (n=20). Psoriasis severity was measured using psoriasis area severity index (PASI). Vascular inflammation was measured using average aortic target-to-background ratio using FDG PET/CT. Results Both the psoriasis patients (28 men, 32 women, mean age 47 years) and controls (13 men, 7 women, mean age 41 years) were young with low cardiovascular risk. PASI scores (Median 5.4; IQR 2.8-8.3) were consistent with mild to moderate skin disease severity. Increasing PASI score was associated with an increase in aortic TBR (β=0.41, p=0.001), an association that changed little after adjustment for age, sex and Framingham risk score. We observed evidence of increased neutrophil frequency (mean psoriasis: 3.7±1.2; vs 2.9±1.2; p=0.02) and activation by lower neutrophil surface CD16 and CD62L in blood. Serum levels of S100A8/A9 (745.1±53.3 vs 195.4±157.8 ng/mL; p<0.01) and neutrophil elastase-1 (43.0±2.4 vs 30.8±6.7 ng/mL; p<0.001) were elevated in psoriasis. Finally, S100A8/A9 protein related to both psoriasis skin disease severity (β=0.53; p=0.02) and vascular inflammation (β=0.48; p=0.02). Conclusions Psoriasis severity is associated with vascular inflammation beyond cardiovascular risk factors. Psoriasis increased neutrophil activation and neutrophil markers, and S100A8/A9 related to both skin disease severity and vascular inflammation.