RT Journal Article SR Electronic T1 Atypical progression of multiple myeloma with extensive extramedullary disease. JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 269 OP 271 DO 10.1136/jcp.47.3.269 VO 47 IS 3 A1 S N Jowitt A1 A Jacobs A1 P A Batman A1 D A Sapherson YR 1994 UL http://jcp.bmj.com/content/47/3/269.abstract AB Multiple myeloma is a neoplastic disorder caused by the proliferation of a transformed B lymphoid progenitor cell that gives rise to a clone of immunoglobulin-secreting cells. Other plasma cell tumours include solitary plasmacytoma of bone (SPB) and extramedullary plasmacytomas (EMP). Despite an apparent common origin there exist pathological and clinical differences between these neoplasms and the association between them is not completely understood. A case of IgG multiple myeloma that presented with typical clinical and laboratory features, including a bone marrow infiltrated by well differentiated plasma cells, is reported. The tumour had an unusual evolution, with the development of extensive extramedullary disease while maintaining mature histological features.