Context

Lymphoid aggregates are seen in a minority of bone marrow biopsy specimens, and when present, their neoplastic nature is often apparent by morphologic evaluation. However, the distinction between benign and malignant aggregates can be a diagnostic challenge when there are multiple aggregates with no documented history of lymphoma.

Objective

To aid in the distinction between benign and malignant B-cell lymphoid aggregates.

Design

Previously, we described specific distribution patterns for B and T lymphocytes within bone marrow aggregates. To statistically analyze the significance of these patterns as well as previously reported criteria, we examined 128 bone marrow specimens with benign aggregates and 78 specimens with documented malignant B-cell aggregates and calculated specific odds ratios (ORs) and 95% confidence intervals (CIs) to aid in differentiating between benign and malignant B-cell aggregates.

Results

Aggregates with infiltrative edges (OR, 80.54; 95% CI, 31.76-204.21), a B-cell pattern (OR, 30.08; 95% CI, 13.28-68.10), paratrabecular location (OR, 10.17; 95% CI, 3.96-26.12), size greater than 600 μm (OR, 6.83: 95% CI, 3.61-12.93), or cytologic atypia correlated with malignancy.

Conclusions

When taken collectively, the presence of more than 2 of these characteristic features was strongly predictive of malignancy.