Objective. To study the relative impact of immunogenetic versus socioeconomic factors on systemic lupus erythematosus (SLE) at disease onsetipresentation.Methods. Medical records regarding SLE onset/ presentation were abstractcd on 229 SLE patients who were enrolled in a prospective lupus outcome study. Patients were grouped in equivalent proportions of Caucasians, African Americans, and Hispanics. HLA-DRB1, DQAl, and DQBl oligotyping, as well as C4 and CR1 allotyping, were carried out by standard methods. In addition to these genetic factors, data on ethnicity, age at SLE onset, monthly income, level of education, and home ownership were entered into stepwise logistic or stepwise multiple linear regression models as independent variables, and each specific clinical feature (neurologic, renal, and cardiovascular disease due to SLE), as well as the total Systemic Lupus Activity

LETTERS Necrotizing vasculitis confined to the nerves: comment on the concise communication by Rosenbaum et alTo the Editor: We read with interest the concise communication by Rosenbaum et al (1) on nonsystemic necrotizing vasculitis of the peripheral nervous system (PNS). While agreeing that vasculitis limited to the PNS has been reported mainly in the neurology literature, we would like to draw the authors' attention to a report in the rheumatology literature about acute necrotizing vasculitis confined to the nerve, with spontaneous recovery (2). A 65-year-old man had presented with leg pains, fever, arthralgias, and weight loss. Muscle enzyme levels were normal. Electrophysiologic studies revealed a symmetric and diffuse polyneuropathy of all 4 limbs, with moderate slowing of motor nerve conduction velocity. A peroneal nerve biopsy revealed a necrotizing vasculitis, while muscle biopsy findings were normal. Interestingly, the patient recovered spontaneously in a few weeks without the use of corticosteroids or other immunosuppressive therapy.We also take this opportunity to describe a similar 21-year-old man we encountered recently. This patient presented with bilateral wasting of the hand muscles and fever. Antinuclear antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, cryoglobulins, and hepatitis B and C serology findings were negative. Urinalysis results were normal, and magnetic resonance imaging of the cervical spine was unremarkable. Electrophysiologic studies revealed asymmetric sensorimotor neuropathy of the mixed axonal and demyelinating type. Sural nerve biopsy showed necrotizing vasculitis. Findings of angiography of the renal, celiac, and superior mesenteric arteries were normal. The patient made a significant recovery when treated with oral corticosteroids and was doing well at 6-month followup.Although muscle biopsy is said to be superior to nerve biopsy for diagnosing isolated neuropathy from necrotizing vasculitis (3), the muscle biopsy findings in the patient described by de la Sayette et al (2) were normal while the peroneal nerve biopsy results confirmed the presence of vasculitis. Our own patient was found to have necrotizing vasculitis by sural nerve biopsy; muscle biopsy was not performed.In addition to vasculitis confined to the skin and nerves, polyarteritis confined to the calf muscles has also been reported (4,5). As of 1993, 9 such patients had been described in the literature (5).Awareness of the existence of limited forms of systemic necrotizing vasculitides helps avoid unnecessary immunosuppressive therapy in such patients.

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