The approach to the treatment of polyarticular juvenile idiopathic arthritis (JIA) is reviewed here and is consistent with the approach outlined in the 2011 American College of Rheumatology (ACR) Juvenile Arthritis Treatment Recommendations [ 2 ]. One exception is that the biologic agents (tumor necrosis factor [TNF] inhibitors) are increasingly used earlier in the treatment course and for less severe disease. The specific agents are discussed in detail separately or in the sections below. (See "NSAIDs: Pharmacology and mechanism of action" and 'Methotrexate' below and 'Tumor necrosis factor (TNF) inhibitors' below.)
Treatment guidelines, based upon presence or absence of active systemic features, clinician global assessment, active joint count, and presence or absence of features concerning for macrophage activation syndrome (MAS), are outlined by the American College of Rheumatology (ACR) [ 2 ]. These guidelines emphasize the earlier use of biologics in children with sJIA, although specific information on appropriate dose is lacking. Another set of standardized treatment plans was developed through a consensus process by the Childhood Arthritis and Rheumatology Research Alliance (CARRA) based upon the most commonly used treatment approaches for systemic JIA [ 3 ].
Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative disorder that occurs during infancy and early childhood; this disorder is characterized by hypersensitivity of the myeloid progenitor cells to granulocyte-macrophage colony-stimulating factor in vitro. JMML usually involves somatic and/or germline mutations in the genes of the RAS pathway, including PTPN11, NRAS, KRAS, NF1, and CBL, in the leukemic cells. Almost all patients with JMML experience an aggressive clinical course, and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. A certain proportion of patients with somatic NRAS and germline mutations in CBL, however, have spontaneous resolution. A suitable treatment after diagnosis and conditioning regimen prior to HSCT are yet to be determined, but several clinical trials have been initiated throughout the world to develop suitable pre- or post-allogeneic HSCT treatments and new targeted therapies that are less toxic, to improve patient outcome.