[Histiocytosis X: excavated macronodular form. Initial alveolar phase with spontaneous regression. Role of smoking]

This is a case report of a 39 year old patient in whom histiocytosis X was discovered following a cough which had appeared several months before. The radiological investigations were distinctive immediately associating the alveolar lesions and the excavated macronodules. The clinical examination was normal but there were some laboratory features suggesting inflammation. The diagnosis was achieved following a surgical biopsy which on histological examination showed histiocytic granulomas and the immunology revealed cells which were positive for OK T6 monoclonal antibodies and S100 antiprotein antibodies. There was subsequently a spontaneous regression with disappearance of the nodular shadows only leaving a few cystic forms. This observation is distinctive and is characterised by the rare appearance of the initial radiology and also confirms the predisposing factor of smoking in the pathogenesis of histiocytosis X.