Clinicopathological features of multiple mononeuropathy associated with systemic lupus erythematosus: a multicenter study.

Multiple mononeuropathy (MM) occurs rarely during systemic lupus erythematosus (SLE) but may lead to major disability. The aim of this study was to investigate the clinic-pathological presentations of MM during SLE, as well as long-term outcomes. We conducted a multicentric retrospective study that included patients receiving a diagnosis of MM during SLE. Ten patients were included (8 women and 2 men, median age at MM diagnosis: 40.4 years). SLE was diagnosed before MM in 9/10 patients (median time 8.2 years). When MM occurred, the SLEDAI score was ≥6 for 6/9 patients. Presenting symptoms consisted of sensory deficits (n = 10), neuropathic pain (n = 9), and/or motor deficits (n = 9), sometimes symmetrical, affecting the lower limbs (10/10) and occasionally the upper limbs (5/10). All patients presented with uni- or bilateral damage of the common fibular nerve, with less frequent involvement of the tibial nerve. Serum cryoglobulinemia was positive in 5/9 patients. Electrophysiological studies confirmed the non-symmetrical involvement of multiple nerve trunks in all patients. Neuromuscular biopsy (performed in five patients) showed histological signs of vasculitis in two patients and perivascular lymphocytic inflammatory infiltrates in two others. All patients were treated with glucocorticosteroids combined with cyclophosphamide (n = 6), rituximab (n = 3), or mycophénolate-mofétil (n = 1). The median follow-up was 5 years. Two patients relapsed during follow-up. All patients had motor and/or sensory sequelae upon follow-up. MM associated with SLE is frequently caused by a vasculitis mechanism. Patients improve with steroids and immunosuppressive drugs. Long-term outcomes include frequent clinical sequelae and possible relapses.