Think outside the box - atypical infections in chronic sinusitis.

Inflammations of the paranasal sinuses represent a common clinical picture. The annual prevalence of chronic sinusitis in Europe is up to 10% [1]. Sinusitis can be divided into acute and chronic forms. In particular, the chronic forms (>12 weeks duration) are often challenging in the context of therapy. In general, all ventilation disorders of the paranasal sinuses (concha bullosa, nasal septal deviations, etc.,) represent risk factors for the development of any form of sinusitis [2]. In addition, an immune deficiency or systemic diseases relevant to the immune system predispose to infections with atypical pathogens. Most sinusitis are caused by viruses, sometimes bacteria and, in rare cases, fungal infections [3]. Furthermore, sinusitis can be differentiated with regard to the affected paranasal sinuses. Unilateral sinusitis can often result from a dental focus and/or a fungal infection such as aspergillosis [4, 5]. However, pathophysiologically, active and chronic sinusitis differ in terms of the sometimes irreversible remodeling processes in the mucosa [6].