The study starts with presentation of present day knowledge of the disease. Its features are predominantly X-ray images consisting mainly in a round or ovular, usually solitary formation ("coin lesion"). The clinical expression of the disease is usually very discrete, the general state unmodified. The X-ray evidencing follows a routine examination. 3 cases of personal observations are presented. All cases were solved by surgery, by removal of tumour. Etiology is fixed by histological examination of surgery specimen. All aspects risen by the differential diagnosis are largely discussed focusing on lung granuloma (e.g. tuberculoma) lung abscess, limited pneumonia, lipoid pneumonia a.o. Hamartomas are of mesenchymal origin, they are not considered just as tumours but very similar to "tumour-like", without invasive evolution.