Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with multi-organ involvement. It may involve skin, kidneys, joints, central nervous system (CNS), and cardiopulmonary system. Marked variations in clinical presentations are seen in SLE patients, ranging from subclinical to life-threatening manifestations. SLE and antiphospholipid syndrome (APS) may be associated with Libman-Sacks endocarditis. Visceral vasculitis usually manifests with disease flares and can affect almost any organ. APS can have arterial or venous thrombosis and the presence of persistently positive antiphospholipid antibodies (aPL), including lupus anticoagulants (LA), anticardiolipin antibodies (aCL), and/or anti-β2-glycoprotein-I antibodies (aβ2GPI). Peripheral neuropathy is unusual in pediatric patients. We present a case of an adolescent girl with juvenile SLE (JSLE) in whom endocarditis and digital gangrene at first presentation were actually masquerading underlying life-threatening secondary APS with extensive medium vessel thrombosis. Additionally, there was cutaneous and visceral vasculitis and a rare peripheral nervous system (PNS) manifestation, mononeuritis multiplex (MNM).
