Lymphadenopathy due to fatal histiocytic proliferative disorder containing Michaelis-Gutmann bodies

A 59-year-old white man had generalized lymphadenopathy, fever, weight loss, and hypercalcemia. Histologic examination of seven lymph nodes from three different anatomic sites revealed a diffuse histiocytic infiltrate containing numerous typical Michaelis-Gutmann (MG) bodies. Histochemical and immunohistochemical results confirmed the histiocytic nature of the predominant cell within the infiltrate. Approximately equal numbers of residual normal B-cells, T-helper, and T-suppressor cells were present. Electron microscopy revealed extracellular and intracellular MG bodies, many of which were membrane-bound. Special stains, electron microscopy, and lymph node culture did not demonstrate microorganisms. The histologic features of the infiltrate were those of malacoplakia. However, the disease behaved like a lymphoma, with the occurrence of lymphadenopathy and a fatal outcome.