A Classical Yet Life-Threatening Presentation of Juvenile Systemic Lupus Erythematosus: A Case Report

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with protean manifestations.Juvenile-onset SLE (jSLE), defined as disease beginning before 18 years of age, accounts for approximately 10-20% of all lupus cases and is characterised by a higher burden of renal and haematological involvement, greater disease activity at presentation and a greater cumulative requirement for immunosuppressive therapy than adult-onset disease.We report a 16-year-old adolescent girl who presented with a photodistributed malar rash, painless ulceration of the soft palate, exertional dyspnoea and a left-sided pleural effusion, with tachycardia (pulse rate 116 beats/min) and hypoxaemia (SpO₂ 88% on room air).Antinuclear antibody was positive, with positivity for anti-double-stranded DNA and anti-Smith antibodies and an elevated C-reactive protein.The patient fulfilled the 2019 EULAR/ACR classification criteria for SLE.Percutaneous renal biopsy confirmed lupus nephritis.She was managed with therapeutic thoracocentesis, high-dose corticosteroids, induction immunosuppression, hydroxychloroquine and supportive care, with clinical and biochemical improvement.This case underscores that mucocutaneous signs that are easily overlooked -in particular a painless palatal ulcer -may be the earliest clue to a severe multisystem autoimmune disease, and that any adolescent presenting with serositis and hypoxaemia warrants prompt autoantibody profiling and early consideration of renal biopsy, since renal histology dictates therapy and long-term prognosis.