The clinical case of Langerhans cell histiocytosis (LCH) in 84-years-old patient with lesions of the skin, lungs, myocardium, liver, pancreas, large intestine, epicardial and periurethral fat, renal hilum fat, mesenteric lymph nodes of small and large intestines and mediastinum, who was unsuccessfully treated for a long time for atopic dermatitis with topical glucocorticosteroids, has been described. There were numerous erythematous spots and papules with hemorrhages, covered with crusts and scales, as well as lichenification and excoriation foci on the body skin on admission at the hospital. Lesions in the lung apices, liver, pericardium, renal hilum, periurethrally and around the superior mesenteric artery had similar morphological picture represented by fibrosis with irregularly distributed infiltration of lymphocytes and histiocytes — large cells with optically dense eosinophilic cytoplasm, as well as of multinucleated cells in histological examination. A pronounced expression of CD1a, S100 and CD207 (Langerin) differentiation markers was found in large cells during immunohistochemical examination of skin biopsy. It is shown that extensive long-term existing dermatitis in an elderly patient, which is resistant to external therapy, proceeding against the background of forming visceral organs pathology, can be an external manifestation of hemoblastosis, including the LCH, which was previously considered exclusively a pediatric disease. Histological and immunohistochemical examinations of the skin are the essential elements for diagnosis establishment in the case of suspected LCH. In addition, the identified dysfunction of the visceral organs, taken by doctors as manifestations of various somatic pathologies peculiar to this age group, may be a manifestation of generalization of the pathological process due to its malignant course.