Comment on: The conundrum of juvenile spondyloarthritis classification: Many names for a single disease? Lesson learned from an instructive clinical case

Abstract

Dear Editor, We read with great interest the paper titled “The conundrum of juvenile spondyloarthritis classification: Many names for a single disease? Lesson learned from an instructive clinical case” by Maniscalco et al1 which emphasizes the complexity of the clinical phenotypes of juvenile spondyloarthropathies (JSpA). All pediatric rheumatologists face these evolving phenotypes of these groups of diseases in their daily practice. To handle these classificational dilemmas, several classification criteria have been proposed for JSpA.2-4 The most recent one, International League of Associations for Rheumatology (ILAR) classification criteria for juvenile idiopathic arthritis (JIA), does not mentioned JSpA as a discrete subgroup and classifies these groups of diseases under three main groups: enthesitis-related arthritis, psoriatic arthritis and undifferentiated arthritis.2 The main concerns about these criteria are: the certain phenotypes of JSpA like inflammatory bowel disease-related arthritis, reactive arthritis were not included in these criteria, and some of the patients are classified as undifferentiated arthritis because of patients fulfilling two subtypes of JIA. It is obvious that these classification criteria are insufficient to reflect all phenotypes of JSpA and there is apparently a need for new sets of criteria.5 The nomenclature for juvenile spondyloarthropathies is not well-defined and still remains enigmatic. This term mainly encompasses enthesitis-related arthritis, psoriatic arthritis, juvenile ankylosing spondylitis, inflammatory bowel disease-related arthritis and reactive arthritis.6, 7 Contrary to adult SpA, JSpA rarely involves the axial skeleton in the early stages of the disease and it usually presents with asymmetric oligoarthritis of lower extremity joints and enthesitis. Therefore, enthesitis-related arthritis can be seen as an early presentation of JSpA. In addition to mentioned diseases, it is also shown that clinical features of JSpA can be seen in the course of familial Mediterranean fever (FMF) and Mediterranean fever gene mutation may be a susceptibility factor for enthesitis-related arthritis especially in regions endemic for FMF.8 In our cohort of patients with FMF, 10.2% of children also fulfilled classification criteria for JSpA.8 Moreover, chronic recurrent multifocal osteomyelitis (CRMO) was suggested to be an unusual form of SpA by several authors and Vittecoq et al9 showed that some of the patients with CRMO developed SpA. The insightful report by Maniscalco et al1 also supports this perspective. In adult patients, rheumatoid arthritis which is the most common cause of adult chronic arthritis and ankylosing spondylitis are well-defined as two distinct phenotypes and both of them have highly accepted classification criteria. In contrast, JSpA is considered under the JIA umbrella in ILAR classification criteria. Yet, this classification criteria obviously are not sufficient to cover this broad spectrum of JSpA (the reasons mentioned above). It is difficult to distinguish between oligoarticular JIA and JSpA especially in the early stages of disease and pediatric rheumatology societies should focus on establishing clearer definitions for JIA and JSpA and developing the new classification criteria which cover all frameworks of JSpA as a distinct disease. We think this approach will not only provide expanded covering but also, better understanding between pediatric and adult rheumatologists. No author of this paper has a conflict of interest, including specific financial interests, relationships and/or affiliations relevant to the subject matter or materials included.