The authors describe three cases of less frequent atypical pneumoconioses. The first patient, a 66 years old woman having been exposed to fireclay dust for 20 years, suffered from silicatosis with concentration of dust in coniophages accumulated in tunica adventitia of small vessels and bronchioles. The other patient, a 57 years old man having worked in various mines, in a quarry and in subway construction for 25 years, suffered from pneumoconiosis from mixed dust with the formation of fibrohyaline nodes and also a macrophage related retention of dust in tunica adventitia of small vessels and bronchioles. In the third patient, a 68 years old man, employed as a welder 34 years ago for four years and later performing welding operations occasionally, we diagnosed a complicated siderosis with severe chronic inflammation, extensive fibrosis and subsequent epidermoid cancer which was then treated by a left-side pulmectomy. An inadequately taken case history made impossible to suspect influence of the dust noxa and the diagnosis was established only by bioptic examination. The authors point out the etiological importance of inhalation exposure to dust and they also discuss how to evaluate the finding of iron deposits in the lungs.

        Key words: pneumoconiosis, silicatosis, siderosis, fireclay dust, welders, lung, iron