Systemic lupus erythematosus is a chronic autoimmune disease accompanied by the synthesis of autoantibodies and the deposition of complement-fixing immune complexes in damaged tissues and organs. Systemic lupus erythematosus has many clinical manifestations, with kidney damage, the so-called lupus nephritis, being one of the most dangerous. The problem of lupus nephritis is especially relevant in pediatric practice, since it is believed that in children the disease is more severe than in adults and is often associated with infant mortality. This article presents modern ideas about the pathogenesis, clinical picture, and therapeutic tactics for lupus nephritis, as well as a clinical observation of class I lupus nephritis occurring with lupus podocytopathy.

age has been demonstrated to be a risk factor for severe bleeding episodes in patients placed on longterm anticoagulation, we decided to start hydroxychloroquine and combination therapy with warfarin (INR range between 2.5 and 3.5) and low-dose aspirin according to EULAR recommendations, considering the patient's good clinical condition and absence of comorbidities. The patient was informed about the nature of the disease and the need for treatment with a high risk of bleeding. In December 2021, despite vaccination with two doses, he contracted COVID-19 infection and warfarin treatment was replaced with low molecular weight heparin at prophylactic dosage, but after some days he presented dyspnoea with desaturation. A lung CT scan showed bilateral pulmonary embolism, attributable to intercurrent viral infection and to APS (not completely controlled after warfarin withdrawal), and so clinicians decided to replace treatment with warfarin. After one month, patient had been discharged from hospital in good clinical health. Conclusions Accurate diagnosis and treatment of late-onset APS represent a challenge due to the lack of knowledge of this disease in the elderly.