[A rare case of so-called idiopathic osteolysis associated with a lymphangioma of the fibula (author's transl)].

: In a 70-year old female patient, a so-called idiopathic massive osteolysis with destruction of the proximal right femur within six months, was observed. Histologically, the following conditions were found at the time of resection: a stroma rich in fibres, with the inclusion of blood vessels, as well as an osteoclastic absorption which was still clearly active at the margins, besides marginally defined processes of bone formation. A good functional result without progressing osteolysis at the femur was achieved via a total endoprosthetic replacement of the right hip joint. Within the following three years, polycystic intramedullar osteolysis developed from a slight loosening of the spongiosa in the right head of the fibula. In contrast to the changes which had occurred at the femur, this was a clear case of a rare intraosseous lymphangioma.