Multiple myeloma with bone marrow biopsy features simulating concomitant chronic idiopathic myelofibrosis.

Multiple myelomas occasionally exhibit bone marrow lesions simulating a concomitant chronic idiopathic myelofibrosis. In the present study, trephine biopsy histologies of such "myelofibrotic" myelomas are described and compared to those from a case of true chronic idiopathic myelofibrosis which developed in the course of chronic lymphocytic leukaemia. "Myelofibrotic" myeloma are characterized by osteosclerosis, marrow fibrosis and focal megakaryocytic hyperplasia in the presence of plasma cell infiltration of the bone marrow. These myelomas are to be distinguished from the more commonly occurring multiple myeloma with simple marrow fibrosis and/or osteosclerosis. Furthermore, "myelofibrotic" myelomas are not identical to myelomas coexisting with true chronic idiopathic myelofibrosis, a condition which would appear to be extremely rare and should only be diagnosed if focal megakaryocytic hyperplasia with atypia can be unequivocally demonstrated. Avoidance of misinterpretation of "myelofibrotic" myeloma requires a knowledge of these different myeloma variants.