SummaryAnatomo-clinical study of a case of reticulosarcomatosis originating in the skin of the frontal region. Gradual extension to most of the face, to several lymph-glands, the mammary gland. Death by thrombosis of both renal veins resulting from the extensive metastatic involvement of both kidneys.Discussion of the mode of metastasis in similar cases, and the possibility of extracellular transmission of a specific infective agent.