Bone marrow trephine biopsy involvement by lymphoma: pattern of involvement and concordance with flow cytometry, in 10 years from a single institution.

Purpose: To evaluate the features of bone marrow (BM) biopsy involvement by lymphoma, pattern of infiltration, morphological analysis and flow cytometry were reviewed at all lymphoma patients over a period of 10 years.

Methods/patients: 413 cases were included in the study if BM biopsy slides were available. Only 356 patients had both BM trephine biopsy and flow cytometry.

Results: The most frequent subtype was diffuse large B cell (31.2%), followed by follicular lymphoma (18.9%). The predominant pattern was mixed (nodular-interstitial) (9.2%). Morphological marrow infiltration was found in 138 cases, and flow cytometry identified 117 cases with BM involvement. A concordance between the two methods was detected in 305 cases (85.7%). There was discordance in 51 cases (14.3%): morphology positive/FC negative in 33 cases and morphology negative/FC positive in 18.

Conclusions: Flow cytometry is slightly more useful in detecting involvement when the BM is affected, but this finding is not conclusive.