[Primary neural leprosy. Report of a case].

We present the clinical manifestations and morphological characteristics in a case from a patient with familial history of leprosy that presented peripheral neuropathy without cutaneous lesions. The nerves affected showed a loss of myelinated and unmyelinated fibers as well as chronic inflammatory infiltrate. The presence of Hansen's bacillus was demonstrated in macrophages, Schwann cells, endothelial cells, and fibroblasts at light and ultrastructural levels. In this case, the demonstration of the bacillus in the biopsy of peripheral nerve confirmed the diagnosis.