Bone marrow histology in myeloma: its importance in diagnosis, prognosis, classification and staging.

A study has been made of 420 bone marrow biopsies from patients with multiple myeloma (220), idiopathic monoclonal gammapathy (50), reactive plasmacytosis (42) and solitary plasmacytoma (22). Histology and immunohistological parameters were more reliable than cytology in distinguishing a reactive from a neoplastic plasmacytosis. Histological variables were correlated with the clinical features of the patients to determine the factors which were of value in predicting prognosis. Plasma cell maturity and the extent of infiltration in the biopsy by myeloma cells proved to be highly significant in predicting the duration of survival. On the basis of these criteria multiple myeloma was classified into two types: plasmacytic of low-grade malignancy and plasmablastic of high-grade malignancy; and into three stages which accurately reflected the progression of the disease. We conclude that a bone biopsy provides useful information for the diagnosis, classification and staging of patients with multiple myeloma.