This paper reports 2 cases of primary hypertrophic osteoarthopathy (PHO) which evolved into secondary hypertrophic osteoarthopathy (SHO) under the influence of bronchogenic carcinoma. The patients had a clinical picture of primary hypertrophic osteoarthropathy but without any signs of disease activity until in the last several months when a malignant bronchopulmonary condition developed. This activated all the symptoms: joint swelling; enlarged fingers and distal forearms and legs; moist palms and soles; unpleasant odour of perspiration; and deeper folds of the forehead and nasolabial furrow. A bone scan showed increased accumulation of the radioisotope in specific regions of the skeleton. To our knowledge, no similar cases have been described in the literature.