Erdheim-Chester disease is a histiocytic neoplasm of diseases from the group of non-Langerhans-cell histiocytoses, formed by infiltrates of foamy histiocytes. These pathological histiocytes produce pro-inflammatory cytokines. Therefore Erdheim-Chester disease is called inflammatory histiocytary neoplasm. The disease is accompanied by clinical symptoms of systemic inflammatory response, i.e. B symptoms. Imaging examinations detect typical osteosclerotic changes affecting diaphyses and metaphyses of the lower long bones and fibrotic changes which affect the aorta wall and the vessels leading from it. Also characteristic are perirenal fibrotic changes spreading in the retroperitoneum. They can cause serious complications - hydronephrosis with all its consequences. The therapy for this disease was not satisfactory in the previous years. Conventional chemotherapy or glucocorticoids do not bring any substantial and long-term improvement. Considering cytostatic drugs, only 2-chlorodeoxyadenosine (cladribine) is effective, though not in all patients. We have only reached complete remission through 2-chlorodeoxyadenosine in one of our two patients, which now lasts more than 5 years, while cladribine in the same patient did effect the reduction of infiltrates into the CNS, but it did not achieve abatement of the disease activity in other locations as shown by PET/CT with the application of the radio-pharmaceutical fluorodeoxyglucose (FDG). Another effective medicine for patients with Erdheim-Chester disease is interferon α. However its long-term administration is associated with multiple adverse effects and so we did not test it in the described patient. The introduction of anakinra, the interleukin-1 receptor blocker, to therapy brought a new hope for these patients. We are describing the patient who has been treated with anakinra for more than 5 years. The patient applies 1 ampoule of 100 mg subcutaneously per day. This treatment completely removed systemic B symptoms, relieved bone pains and attained normalization of all findings that signalled systemic inflammatory response. The treatment effect is regularly checked by CT imaging of the abdomen and by FDG-PET/CT examinations. The retroperitoneal fibrotic changes gradually regressed during the 5 years of anakinra treatment, as documented by the pictures in the text. Low-dose CT imaging which was part of the PET/CT examination, identified many osteosclerotic lesions in the skeleton, mainly in the legs, with an increased accumulation of 18F-fluorodeoxyglucose (FDG). Osteosclerotic lesions remain well visible at repeated examinations. Still during the course of the 5-year period the FDG accumulation in them decreased, as shown by the pictures in the text. Anakinra treatment has a character of maintenance therapy. The BRAFV600E mutation was not proven in the described patient, therefore we did not test vemurafenib treatment.
anakinra effected regression of fibrotic changes in the retroperitoneum and disappearance of B symptoms as well as decrease in FDG accumulation at FDG-PET/CT examination.Key words: anakinra - Erdheim-Chester disease - cladribine - retroperitoneal fibrosis - vemurafenib.