Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease of hair follicles which is associated with various comorbidities. The aim of our study was to clarify the associations between HS and psychiatric disorders.We conducted a nationwide retrospective study that included 4381 patients with HS and 39554 psoriasis and 43248 melanocytic nevi (MN) patients as controls Patient data were obtained from the statutory Finnish Care Register for Health Care. Statistical analyses were performed using STATA and the SAS software package.The incidence of HS in Finland was 2.7/100,000 persons/year. At least one psychiatric diagnosis was found in 24.1% of the HS patients compared with 19.1% of those with psoriasis (odds ratio [OR] 1.34; 95% confidence interval [CI] 1.24u20131.46) and 13.5% of those with MN (OR 2.04; CI 1.88-2.22). Every mental disorder examined was significantly more frequent in HS than in the two other groups. Major depression was more common in the HS group than in the psoriasis (15.3% vs. 12.1%, OR 1.31, 95% CI 1.19u20131.44) and in the MN group (8.3%, OR 2.00, 95% CI 1.81-2.22). Anxiety disorders were diagnosed in 6.9% of HS patients compared with 5.0% of those with psoriasis (OR 1.41, 95% CI 1.23 - 1.62) and 3.8% of those with MN (OR 1.90, 95% CI 1.65-2.19). The total prevalence psychotic disorders was 4.7% in the HS group compared with 3.3% in the psoriasis group (OR 1.46, 95% CI 1.24u20131.72) and 1.7% the MN group (2.74, 95% CI 2.29-3.28). Specifically, u201cschizophrenia or schizotypal disorderu201d was more frequent in the HS group than in patients with psoriasis (2.4% vs. 1.5%, OR 1.57, 95% CI 1.24u20131.98) or in patients with MN (2.4% vs.0.7%, OR 3.38, 95% 2.59-4.39).The main finding of our study is that HS patients have a higher risk for mental disorders than patients with psoriasis. For dermatologists treating HS patients it is important to take into account the high psychiatric comorbidity burden in HS.

Bullous pemphigoid (BP) is the most frequently occurring autoimmune blistering skin disease. Recently several epidemiological studies have demonstrated that dipeptidyl peptidase-4 inhibitors (DPP-4i or gliptins), widely used in the treatment of diabetes, increase the risk of BP. BP associated with gliptin treatment has often classical BP characteristics, but may also display atypical in phenotype and immunological findings.The aim of our study was to clarify whether BP cases previously treated with gliptins have special features. We also explored the expression of DPP-4/CD26, BP180 and its binding partner laminin gamma-2 in the skin of BP patients, and the effect of gliptins on their expression in cultured keratinocytes. We analyzed the clinical, histopathological and immunological features of 27 BP patients 10 of whom had preceding gliptin medication. The expression of DPP-4/CD-26, BP180 and laminin-uf0672 in skin samples was investigated by immunohistochemistry and their expression in DPP-4i-treated keratinocytes by immunoblotting. Compared to those who had not, subjects who had previously received gliptins had lower BP180-NC16A ELISA values, fewer neurological co-morbidities and shorter time to remission, but differences were not statistically significant. The HLA-DQB1*03:01 allele was more common among BP patients in general than in the control population, but was not more common in those with gliptin history. The skin expression of DPP-4/CD-26 was increased of BP patients, but not affected by prior gliptin treatment. The treatment of keratinocytes with gliptins elevated the amount of BP180 and laminin gamma-2, but the increases were not statistically significant.DPP-4i medication is common among BP patients and prior gliptin treatment may be associated with some specific features. The expression of DPP-4/CD-26 is elevated in BP skin, regardless of previous gliptin intake, underlining the role of DPP-4/CD-26 in inflammatory processes in general.