Sural nerve biopsy in vasculitic neuropathies: morphometric analysis of the caliber of involved vessels.

We performed histologic and morphometric analyses of the sural nerve in 13 patients with vasculitic neuropathies. The ratio of vessels with vasculitis, the caliber of involved vessels, and pathologic changes of myelinated fibers were evaluated. In patients with polyarteritis nodosa (PN), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE), marked vasculitis with inflammatory cell infiltration and occlusion were observed in epineurial arteries greater than 100 microns in diameter, and mild vasculitic changes were noted in arterioles 40 to 100 microns in diameter. In vessels less than 40 microns, mild vasculitis with perivascular cuffing was noted in patients with RA and SLE, but not in PN. In a patient with microscopic PN, mild inflammatory cell infiltration was encountered around small vessels at diameters less than 40 microns as well as those greater than 100 microns. In a patient with nonsystemic vasculitic neuropathy, vasculitic changes were identified only in vessels less than 40 microns. In patients with Churg-Strauss syndrome (CSS), there were no distinct findings of vasculitis in any biopsy material. In conclusion, morphometric analyses of the caliber of involved vessels may be useful in the differential diagnosis and classification of underlying vasculitic neuropathies.