The many faces of sarcoidosis. The Thomé Villar memorial lecture.

Sarcoidosis wears many different faces, depending upon the viewer, who may be clinician, radiologist, pathologist or immunologist. This Thomé Villar Memorial lecture salutes the charismatic chest physician who pioneered studies of the disorder in Lisbon and transmitted this knowledge internationally. The four main themes of this Lisbon Conference are granuloma formation, granulomatous vasculitis, markers of activity and occupational granulomatous lung diseases; these four faces of sarcoidosis are delineated in the way that they are recognised today and as they might unfold tomorrow. Sarcoid granuloma formation is the result of a complex interplay of invading antigen, prolonged antigenaemia, macrophage presentation, T4 response, B cell overactivity, circulating immune complexes and a cascade of several biological mediators. This spider's web progresses to fibrosis which represents a process of reparation leaving a scarred hyalinised remains of the previous battlefield. Granulomatous vasculitis embraces a group of disorders which mimic sarcoidosis. Assessment must include markers of activity to decide whether sarcoidosis is active and progressive. Lisbon is an international centre for the study of occupational granulomatous lung disease and its differentiation from sarcoidosis. Finally four important remaining problems concerning sarcoidosis are faced. They are: 1. What is the aetiology? 2. Who develops it and why? 3. What are the best ways of assessing activity? 4. How is it best treated?