SP0077 CASE DISCUSSANT
Authors: Brigitte Bader-Meunier
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Pediadiatric-onset systemic lupus (pSLE) is a severe mulisystem autoimmune condition which mostly manifests after the age of 10 years. It is mainly a polygenic disorder, but a mutation in a single gene may predispose to the developementof SLE (« monogenic lupus »). We will describe some unusual presentations which may lead to a delayed diagnosis or misdiagnosis and provide clues for the diagnosis of monogenic lupus. <h3>Objectives:</h3> To discuss the difficult diagnosis and pitffalls in pSLE <h3>Results:</h3> The most common initial manifestations of pSLE are cutaneous, musculoskeletal, renal, hematologic, and fever. Howerver, atypical symptoms may reveal the diagnosis or occur during the course of SLE. In a French retrospective study<sup>1</sup>, thirty-two percent of children had atypical symptoms, mainly including abdominal involvement in 26 patients, which lead to negative laparotomy for presumed appendicitis before the diagnosis of SLE could be established. Abdominal pain was related to lupus pancreatitis or peritonitis. The diagnosis of pSLE should be systematically searched for in a teenager who presents with unexplained mood disorders, psychosis or depression, which may reveal pSLE. In a patient with a suspected diagnosis of neuropsychiatric pSLE, underlying factors including infections, hypertension, metabolic abnormalities or adverse effects of medication should be excluded before considering a luous-related neurological involvement<sup>2</sup>. Finally, the diagnosis of pSLE should be also considered in case of severe complications such as macrophage activation syndrome or alveolar hemorrhage. Monogenic SLE should be suspected in early-onset SLE (&lt; 5-year-old) and mainly comprise complement deficiencies, genetic overproduction of interferon-α, B-cell apoptosis defects and rare inherited immunodeficiencies. Each of these conditions is associated with specfic features : 1) Primary complement defects are associated with recurrent pyogenic or neisserial infections 2) type-1 interferonopathies are often associated with spasticity, cerebral calcifications, encephalopthy, skin ulcers and chilblains, and, in some cases, with a growth delay (spondylenchondrodysplasia) 3) B-cell apoptosis defects (mutation in <i>PRKCD</i> gene) is associated with a lymphoproliferative disease. A proper diagnosis of SLE must therefore be based upon a complete family medical history as well as on clinical evaluation with details history of both present and past illnesses, analysis of growth chart as well as laboratory tests for SLE. The search for auto-antibodies towards nuclear antigens is a key step in the diagnosis strategy, keeping in mind that antinuclear antibodies are not specific for SLE. Screening for complement deficiencies via CH50, AP50, C3 and C4 is recommended in order to facilitate adequate treatment of comorbidities including infections<sup>2</sup> in pSLE patients<sup>2</sup>. <h3>Conclusion:</h3> The diagnosis of pSLE should be suspected in teenagers with acute unexplained symptoms, especially in case of abdominal pain or neuropsychiratric involvement. A monogic predisposition to SLE should be considered in early-onset SLE, especially in patients with SLE family history, consanguinity, recurrent infections, and/or encephalopathy with spasticity. <h3>References:</h3> [1] Bader-Meunier B, Armengaud JB, Haddad E, et al. Initial presentation of childhood-onset systemic lupus erythematosus: a French multicenter study. J Pediatr. 2005;146(5):648-53. [2] Groot N, de Graeff N, Avcin T, et al. European evidence-based recommendations for diagnosis and treatment of childhood-onset systemic lupus erythematosus: the SHARE initiative. Ann Rheum Dis. 2017;76(11):1788-1796 <h3>Disclosure of Interests:</h3> None declared