Studies that report the incidence of bullous pemphigoid from validated nationwide population-based registries are rare. The aim of this study was to estimate the incidence of bullous pemphigoid in Sweden 2005–2012. A population-based open cohort study was designed including all patients diagnosed by a dermatologist with bullous pemphigoid (BP) in Sweden from 2005 to 2012 (n = 3761), identified from the National Patient Register (NPR). The diagnosis of bullous pemphigoid in the NPR was recently validated from medical records, histopathological and immunopathological data by our group in a previous study. The average annual incidence of bullous pemphigoid was 7.1/100,000 (95% CI 6.5–7.7). Female to male ratio was 1.2:1, mean age at diagnosis was 78.9 years. The age-specific incidence rate increased markedly after 80 years of age with an incidence peak between 90 and 99 years of age, 81.9/100,000 (95% CI 75.0–89.2). This large nationwide cohort study presents an adjusted incidence of BP of 7.1/100,000 (95% CI 6.5–7.7) in Sweden. The incidence of bullous pemphigoid is higher than expected and bullous pemphigoid is a common disease in the elderly population.

Since the symptoms of psoriasis may be changed by treatment with selective serotonin reuptake inhibitors (SSRIs), the expression of serotonin (5-HT) and its transporter protein (SERT) in the skin of patients with psoriasis were examined employing a biotinylated-streptavidine procedure. In biopsies of such skin staining for 5-HT was limited to platelets; the expression of SERT in the keratinocytes of involved regions was redistributed; the numbers of SERT-positive dendritic or round mononuclear cells in the epidermis of involved psoriatic skin were higher than in normal healthy control skin; and the dermis of the involved skin contained higher numbers of round inflammatory cells immunostained for SERT than either non-involved psoriatic skin or normal skin. Double-immunostaining indicated that the skin cells expressing SERT also expressed CD1a, CD3 or tryptase. In addition, SERT immunostaining was co localized with caspase-3, a key regulator of apoptosis, but not with TUNEL staining. The present findings indicate that SERT might play a role in regulating apoptosis in inflammatory cells associated with psoriasis, in which case this protein might constitute a valuable therapeutic target.

Abstract. Thorslund K, Svensson T, Nordlind K, Ekbom A, Fored CM (Karolinska Institutet, Stockholm; Sweden). Use of serotonin reuptake inhibitors in patients with psoriasis is associated with a decreased need for systemic psoriasis treatment: a population-based cohort study. J Intern Med 2013; 274: 281-287.Objective. To investigate whether psoriasis is affected by the use of serotonin reuptake inhibitors (SSRIs).Design. A population-based cohort study. Subjects. A total of 69 830 patients with plaque psoriasis were identified in the National Patient Register. Whether study subjects were exposed to SSRIs was identified through the Swedish Prescribed Drug Register. The SSRI-exposed subjects (n = 1282) had a prescription for SSRIs dispensed twice during 6 months at a Swedish pharmacy between 1 July 2006 and 1 April 2008, with a wash-out period of 1 year or longer. The reference subjects (n = 1282), who were not exposed to SSRIs, were matched for age, county of residence, sex, psoriasis severity and seasonal variation.Main outcome measure. Change in psoriasis severity defined by switching between nonsystemic and systemic psoriasis treatments 6 months after exposure to SSRIs.Results. The risk of switching from nonsystemic to systemic psoriasis treatments was significantly decreased in the SSRI-exposed group (odds ratio 0.44, 95% confidence interval 0.28-0.68).Conclusion. SSRI use in patients with psoriasis is associated with a decreased need for systemic psoriasis treatment.

Bullous pemphigoid (BP) is the most common autoimmune blistering disease. Since 2001, data from all specialized outpatient and inpatient care institutions in Sweden, have been registered with the National Patient Register (NPR), based on a unique personal identification number. Previous validations of the register have shown high accuracy for various non-dermatological autoimmune diseases. In order to validate the diagnosis of BP, all residents aged < 20 years in 2 counties in Sweden (539,000 inhabitants) diagnosed with bullous pemphigoid (ICD-10; L12.0, L12.8, L12.9) in the period 2001 to 2012 were identified in the NPR. Medical records, as well as immuno- and histopathological data, were reviewed for this study. A total of 323 patients with BP were identified in the NPR. Of these, 178 patients had a directly confirmed diagnosis of BP from immuno- and histopathological data, reviewed by a dermatopathologist. For the remaining 145 patients medical records were retrieved and further reviewed by 2 dermatologists. Of these, 105 patients had a confirmed diagnosis of BP. The medical records of 16 patients were missing, and 24 patients were not classified as having BP. Overall, a positive predictive value of 92% (283/307) was found for BP in the NPR. In conclusion, the present validation of medical records and immuno- and histopathological data showed high validity for the diagnosis of BP in the Swedish NPR.

Psoriasis may be worsened by stress and mood disorders. There is an increased expression of the serotonin transporter protein (SERT) in involved psoriatic skin as compared to non-involved psoriatic skin and normal skin. The aim of this study was to investigate if the increased expression of SERT in psoriasis correlates with the severity of disease, chronic stress, and depression. Biopsies from involved and non-involved skin from the back of 20 patients with chronic plaque psoriasis were immunohistochemically analysed, using a monoclonal antibody to SERT. The severity of psoriasis was assessed for each patient using the Psoriasis area and severity index (PASI). Levels of depression and chronic stress were measured using Beck's Depression Inventory (BDI) and the salivary cortisol test, respectively. A positive correlation (r = 0.53; p < 0.05) between PASI and the numbers of SERT-positive dendritic cells in the epidermis of involved psoriatic skin was determined. We also observed a negative correlation (r = -0.46; p < 0.05) between salivary cortisol ratio levels and the numbers of SERT-positive cells in the epidermis of involved psoriatic skin, indicating a correlation between SERT expression and chronic stress. The serotonergic system may be involved in the chronic inflammation evident in psoriatic skin. Through modulating the levels of SERT, there might be a therapeutic possibility for reducing chronic inflammation in psoriasis.