Autoimmune bullous diseases in non-HIV Kaposi's sarcoma : a retrospective study in a large cohort of patients

Background: Kaposi's sarcoma (KS) is a rare endothelial neoplasm caused by the human herpesvirus 8 (HHV-8). Its risk is increased in immunocompromised patients, including those undergoing immunosuppressive therapy for autoimmune bullous diseases. Conversely, HHV-8 infection has been hypothesized to be a triggering factor of bullous diseases, especially pemphigus. Given the fact that both KS and autoimmune bullous diseases have a low incidence in the general population, it could be expected that the association between these disorders would be exceptional. Objectives: To assess the frequency of bullous diseases in a large cohort of non-HIV KS patients and to describe our experience concerning the clinical features, natural history and treatment options in this setting. Methods: We performed a retrospective review of all patients with non-HIV KS in association with bullous disease followed at our department between 1990 and 2016. Medical records were reviewed for demographics, medical history, clinical characteristics and treatment. Results: Among 1362 patients with classic or iatrogenic KS, 14 (1.03%) also suffered from bullous disease. The mean age at diagnosis of both disorders was 85.8 years with a male/female ratio of 9: 5. Among these 14 cases, nine (0.66%) were associated with bullous pemphigoid (BP), three (0.22%) with localized BP and two (0.15%) with pemphigus vulgaris. Seven had developed a bullous disease after being diagnosed with KS, while in the remaining seven cases, KS developed after the onset of bullous disease. As expected, KS worsened when corticosteroids were used. Conclusion: Bullous diseases seem to be more frequent among patients with KS, supporting the hypothesis that HHV-8 may be involved in their pathogenesis. Therapeutic management of these cases should take into account KS-inducing potential of corticosteroids.