Introduction

Abstract

The etiology and pathogenesis of diseases that show synchronous or metachronous involvement of the skin, mucous membranes, and bones are well known in the case of some entities but are poorly understood in others. For example, in patients with mucosal inflammations due to immunvasculitis, symptoms will appear concomitantly or sequentially in anatomic regions with mucosal structures, involving for example the eyes, mouth, gastrointestinal tract, pleura, or the large and small joints of the axial and appendicular skeleton. While we know that the symptoms (e.g., conjunctivitis, diarrhea, joint swelling with limited motion) are based on the location of the inflamed mucosae, we do not yet know the principles that govern the timing of involvement of different organ systems in certain diseases.