Lymphoid aggregates in bone marrow: study of eventual outcome.

The practical importance of finding a morphologically benign lymphoid aggregate in the bone marrow of patients without known lymphoproliferative disease was assessed in 786 consecutive patients who had had 951 iliac crest bone marrow biopsies performed. Of these, 430 patients known to have lymphoproliferative disease at the time of biopsy were excluded. Of 356 patients, 86 (aggregate group) had at least one lymphoid aggregate in their biopsy specimen biopsy specimen (82 morphologically benign, three suspicious, and one malignant). Another 86 patients without aggregates (control group) were matched by age and sex. Both groups were followed up until death, or for a mean of 21.9 and 22.9 months, respectively, to assess their outcome. Eighteen (22%) of the 82 patients with morphologically benign lymphoid aggregates were later proved to have lymphoproliferative disease compared with none of the 86 control patients. Another 12 patients in the aggregate group and seven in the control group were suspected of having a lymphoproliferative disease on clinical grounds, so that altogether 30 (37%) and seven (8%), respectively, developed confirmed or suspected lymphoproliferative disease. In both cases the differences were highly significant (p less than 0.001). It is suggested that lymphoid aggregates in clinical biopsy material may not be a physiological finding and should alert pathologists or haematologists to the possibility of lymphoproliferative disease.