The clinical case of debut of Lagerhans cell histiocytosis under the rheumatological disease mask

A pediatrician faces with the differential diagnosis of oncological, oncohematological diseases which could have rheumatological "masks". According to medical literature, the most important symptoms are the joint pain at night, diffuse bone pain and organomegaly. Among the laboratory markers of oncological/oncohematological diseases the most important are bi-/trilineage cytopenia, high level of ESR, LDH, uric acid; including in the differential diagnosis of the neoplastic process in the detection of unilateral sacroiliitis without damage of other joints is necessary. The clinical case of a patient with Lagerhans cell histiocytosis is presented for differential diagnosis with the debut of spondyloarthritis for increasing the alertness of pediatricians and rheumatologists in children with musculoskeletal pain. Key words: Lagerhans cell histiocytosis, juvenile idiopathic arthritis, juvenile ankylosing spondylitis