New information is presented on the etiology, pathogenesis, clinical manifestations and histological characteristics of a rare pathology of the skin and bones of the extremities — pachydermoperiostosis. Three main clinical signs characterize primary pachydermoperiostosis: pachyderma of the face, periostosis and changes in the distal phalanges of the fingers, occurs more often in men and begins in adolescence. The secondary form of the disease develops in men of mature age with severe lung lesions, less often with cancer of the stomach, esophagus or thymus. The clinical picture is dominated by bone changes; skin changes may be absent or insignificant. Histological examination of the skin reveals a thickening of the dermis due to an increase in the number of collagen and elastic fibers, proliferation of fibroblasts, small perivascular and perifollicular lymphohistiocytic infiltrates, enlargement of the mouths of hair follicles with accumulation of horny glands in them, hyperplasia of sebaceous, sometimes sweaty glands. In addition, the article highlights the difficulties of differential diagnosis of this disease with other dermatoses. A clinical case of pachydermoperiostosis in a man aged 19 years is described. The patient underwent an assessment of the disease clinical picture, the hormonal activity of the pituitary gland, instrumental studies. Treatment with etoricoxib 90 mg once a day was prescribed to relieve articular syndrome. After 3 months of treatment the pain in the knee joints, interphalangeal joints of the feet became less pronounced.