Lymphoid follicles in bone marrow aspirates.

Lymphoid follicles were observed in 260 of 1,450 consecutive bone marrow aspirates (17.9%). As expected, the incidence of lymphoid follicles was less than those reported from autopsies (26.1-62.3%), but was twice as great as those in previous reports based upon study of aspirations (3.3-9.1%). The number of lymphoid follicles is also related to age and sex of the patient: they are rare in childhood and common after the fourth decade of life, particularly in women. Lymphoid follicles are found in higher incidence in bone marrow aspirates with plasma-cytosis and/or lipid granulomas than in those without these reactive changes. This relationship has not been described previously and suggests that the frequent occurrence of lymphoid follicles in the older age group may be a minifestation of a response to chronic immunologic stimulation.