Peripheral neural involvement in cutaneous leishmaniasis. A pathologic study of human and experimental animal lesions

Peripheral neural involvement in cutaneous leishmaniasis has recently been recognized. A man presented with several tender hyperesthetic skin nodules. Histopathologic examination confirmed the diagnosis of cutaneous leishmaniasis. Of most interest was the presence of a striking lymphohistocytic inflammatory infiltrate around and within cutaneous nerves in addition to demonstrable leishmania organisms in the perineural space. This observation led to a detailed histopathologic evaluation of leishmanial skin lesions that developed in 13 mice after subcutaneous injection with leishmania major promastigotes. Varying degrees of neural involvement was noted in skin lesions from nine animals. In some lesions, in addition to inflammatory cells in the nerves, organisms were demonstrable within probable schwann cells. Three pathologic stages of dermal neural involvement were identified, namely, an early, intermediate, and late stage, depending on the severity of damage; however no correlation was found between the pathologic stage and the duration of the leismanial skin lesion of a specific animal.