THU0546 Impact of bone localisation on the prognostic of langerhans cell histiocytosis: a monocentric retrospective study
Authors: J-G Letarouilly, N Segaud, B Wallaert, P-Y Hatron, R-M Flipo
Journal: Annals of the Rheumatic Diseases (2017)

<h3>Background</h3> Langerhans cell histiocytosis (LCH) is a rare condition, and mostly affects children. Bone is the most commonly involved organ, with bone lesions in 50% of patients. In a recent work, Aricò et al. described that the probability of survival in children suffering from a multisystemic LCH with risk organ involvement was reduced if patient did not have any bony lesion [1]. There is no such a study in adult patients. <h3>Objectives</h3> The objective of the study was to know the bone impact on the prognosis of adult LCH. <h3>Methods</h3> A retrospective monocentric study was performed using data from the patients hospitalized for a LCH at Centre Hospitalier Régional Universitaire de Lille, a university hospital between 2001 and 2015. All patients with LCH and at an age of 18 years or older were included. Patients were excluded if they did not receive any osteoarticular imaging (radiography, scintigraphy, PET, MRI). <h3>Results</h3> Our study initially included 70 patients had LCH. After screening 54 patients met the inclusion criteria: 31 had bone localization (BLG) and 23 none (NBLG). The two groups showed differences. The lesion leading to the diagnosis was mostly osteoarticular (18 patients) in BLG and pulmonary (18 patients) in NBLG. The BLG presented more multisystemic form than the NBLG (20 vs 2, p&lt;0.0001). Both groups were equivalent for comorbidities (p=0,206 for cancer and p=0,756 for cardiovascular disease), number of smokers and age at diagnosis (36.8+/- 14.15 years vs 36.7+/- 12.6 years, p=0.96 and 25 vs 22, p=0.06). Treatment was required for 14 patients in BLG and for 2 in NBLG. In BLG, 8 patients were treated medically, mostly by corticosteroid therapy and chemotherapy (7), one patient underwent radiotherapy. 6 patients were treated by surgery. In NBLG, 2 patients were treated by corticosteroid therapy. There was no surgery in NBLG (table 1). 3 patients died in BLG, 2 directly related to LCH and one from postoperative infectious complications. One patient died in NBLG from hematologic pathology (chronic myelomonocytic leukemia). The time between diagnosis and death was one, six and 22 months in BLG, 36 months in NBLG. 7 patients presented relapses in BLG. 5 had been treated by medical treatment, one surgically and one had no previous treatment. The time of relapse was six, 8, 12, 14, 16, 52 and 72 months. 4 presented new bone lesions, 1 pulmonary lesions, 1 dermatologic lesions and 1 neurologic lesion (table 1). There was no relapse in NBLG. Unfortunately, there was a lack of statistical power to conclude about the bone impact on the prognosis. <h3>Conclusions</h3> Patients with bone location and those with no bone location are two different phenotypes of adult LCH. Patients with bone location are more proned to have a multisystemic relapsing disease. A multicentric study with a larger number patients is needed to bring more robust data to answer about bone impact on the prognosis of adult LCH. <h3>References</h3> Aricò M, Astigarraga I, Braier J, et al. Lack of bone lesions at diagnosis is associated with inferior outcome in multisystem langerhans cell histiocytosis of childhood. Br J Haematol 2015;169:241–8. <h3>Disclosure of Interest</h3> None declared