Acute pure sensory paraneoplastic neuropathy with perivascular endoneurial inflammation: ultrastructural study of capillary walls.

We studied a patient with epidermoid carcinoma of the lung (treated surgically 1 year earlier) and an acute symmetric pure sensory neuropathy that regressed almost completely within 1 month. Superficial peroneal nerve biopsy 15 days after onset showed evidence of demyelination with perivascular endoneurial inflammation. On ultrastructural examination, lymphocytes were seen passing through endothelial cells of endoneurial capillaries.