The cellular basis for extremity bone loss in leprosy.

Osteoclasts and osteolytic osteocytes have been observed in the majority of 60 samples of bone taken from five patients with lepromatous or tuberculoid leprosy. These results are interpreted to mean that bone loss in patients with leprosy is an acceleration of a normal cellular process and not the result of avascular necrosis. The acceleration of bone resorption could be due to local release of products from M. leprae or host cells, a hypothesis testable by organ culture methods. The presence of lymphocytes and mononuclear cells in bone samples in this and previous studies is discussed with respect to recent evidence of a role for lymphoid cells in bone resorption.