Staging FDG PET/CT prediction of bone marrow involvement by diffuse large B-cell lymphoma leading to delayed recognition of multiple myeloma.

BACKGROUND

18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scans have largely replaced bone marrow biopsy in the staging workup for diffuse large B-cell lymphoma (DLBCL).

PURPOSE/

METHODS

Here, we highlight a pitfall of FDG PET/CT for assessing bone marrow involvement, detailing the clinical course of a patient diagnosed with otherwise limited-stage DLBCL who exhibited diffuse bone marrow FDG uptake, felt to be compatible with extensive lymphomatous infiltration. In accordance with current National Comprehensive Cancer Network guidelines, this finding circumvented the need for a formal staging bone marrow biopsy procedure.

RESULTS

Subsequent clinical developments revealed extensive bone marrow involvement by a second, unexpected malignancy (multiple myeloma), casting doubt on the assumption that the initial diffuse marrow uptake was attributable to DLBCL.

CONCLUSION

The presented case emphasizes the challenges of interpreting diffuse FDG uptake within the bone marrow compartment and highlights the inherent contribution of histomorphology for the accurate diagnosis and classification of hematolymphoid neoplasms.