Stromal changes in leukaemic and related bone marrow proliferations

Abstract

The stromal struc-ture of the bone marrow was studied in 96 cases of leukemia and related disorders. The reticulin stroma forms an integral component of any given marrow proliferation and may often be increased in amount, sometimes normal, and occasionally decreased. The pattern is often indeterminate but certain distinguishable patterns may be found, including a sinusoidal pattern in myelofibrotic chronic myeloses, a pattern characterized by an abundance of hyperplastic capillaries and arterioles often seen in lymphoid leukemias, and one with irregular focal reticulin proliferation in many acute undifferentiated leukemias. Adventitious collagen fibres are demonstrable in about half of all myeloses, acute and chronic, leukemic and aleukemic, and may be diffuse or focal. They apparently develop from thickening and collapse and condensation of the basic reticulin network, not from any primary fibroblastic proliferation. The development of fibrosis does not denote an etiological relationship between the conditions in which it occurs, since it appears to be a nonspecific sequel to marrow exhaustion and marrow necrosis. There is no justification for the diagnosis of acute or ''malignant'' myelofibrosis as a disease entity in cases of acute leukemia with marrow fibrosis. Osteolytic change due to resorption of bony trabeculae is a common event in all the conditions studied and may be accompanied by remoulding of the eroded trabeculae. Fibre bone formation is found in about 15% of cases, including acute lumphoblastic leukemias and acute undifferentiated leukemias, but is extensive and well-developed only in cases of primary myelofibrosis.