Diagnostic value of bone marrow biopsy in primary extranodal non-Hodgkin lymphomas: a comparative analysis of trephine biopsy, myelogram, and PET/CT

Objective. To determine the frequency of bone marrow (BM) involvement in various types of primary extranodal non-Hodgkin lymphomas (NHL) and to compare the findings of 18F-FDG PET/CT and myelogram with histological data from BM core biopsies. Material and methods. A retrospective analysis was conducted on 86 patients (aged 18—79 years) diagnosed with primary extranodal NHL between 2020 and 2025. All 86 patients underwent 18F-FDG PET/CT, and 63 patients concurrently received a BM myelogram. Statistical analysis was performed using Fisher’s exact test, McNemar’s test, and Cochran’s Q test for related samples. Results. BM involvement was histologically verified in 24.4% (n=21) of patients. The frequency of BM infiltration was significantly associated with the histological subtype of primary extranodal NHL (p=0.014), with diffuse large B-cell lymphoma being the most prevalent, accounting for 28.57% (n=6) of all detected BM lesions. When comparing 18F-FDG PET/CT with histological analysis (n=86), the results concorded in 77.9% of cases (n=67: 10 true-positive and 57 true-negative). False-positive and false-negative PET/CT results were observed in 9.3% (n=8) and 12.8% (n=11) of cases, respectively. In the cytology subgroup (n=63), the myelogram indicated BM involvement in only 9.5% (n=6) of patients. Comparative analysis revealed a 17.5% (n=11) false-negative rate and a 3.2% (n=2) false-positive rate for the myelogram; differences compared to histology were highly significant (p=0.018). Conclusion. The findings of this study demonstrate the high diagnostic value of histological evaluation of BM core biopsies during the staging of primary extranodal NHL.