Clinical observation of Erdheim–Chester disease: diagnostic difficulties, treatment options

As is known, orphan diseases, which include histiocytosis, including Erdheim-Chester disease (ECD), occur under the guise of other diseases, which complicates timely diagnosis and treatment. The presence of various symptoms in patients with an unspecified diagnosis (weight loss, fever, chills, night sweats, malaise, shortness of breath, thirst, polyuria; pain in the muscles and joints, in the long tubular bones of the upper and lower extremities, in the lower back or abdomen due to kidney damage and/or retroperitoneal fibrosis; exophthalmos; rash, xanthomas; frequent infectious diseases; nystagmus, ataxia, dysarthria) requires doctors to be wary of BEC.The variety of symptoms is due to the involvement of many organs and systems (orbits, kidneys, skin, brain, including the pituitary gland; lungs; heart; blood vessels; tubular bones), which requires a thorough examination, including morphological verification of the pathological process. Histological examination of biopsy specimens for BEC is characterized by histiocytic infiltrates (so-called “foamy histiocytosis”) with signs of inflammation and the presence of Touton giant cells; Immunohistochemistry reveals positive staining of these giant cells for CD68 antigen and factor XIIIa. Bone scintigraphy reveals a pronounced symmetrical accumulation of radiopharmaceuticals in the affected bones; with radiography in places of ossalgia — significant symmetrical bilateral osteosclerosis of the periosteum; according to CT data - “hairy” kidneys, “lined” aorta as a result of infiltration with histiocytes. The BRAF V-600E gene mutation, detected in half of the cases, in combination with one or more clinical and morphological signs allows a correct diagnosis to be made. The treatment of this disease is quite complex due to the lack of multicenter international clinical studies due to the rare occurrence of this pathology. However, clinical studies are currently being conducted on the use of drugs of various groups in the treatment of BEC. There is no doubt that due to the rarity of the disease and the low awareness of doctors, our own clinical experience in managing such patients is of great interest.