5. Conclusion
These cases emphasize the importance of multimodality approaches, highlights the role of the 18F-FDG PET/CT to detect rare or unusual HCL involvement and to drive biopsy. Although only small series of patients have been reported in the literature, atypical presentation in HCL is not uncommon and represents a significant diagnostic challenge in routine practice. 18F-FDG PET/CT should become more prominent in the future at the time of diagnosis and in monitoring response in cases of unusual or atypical presentation. However, the pathological mechanism of this bone involvement with such low bone marrow involvement remains unclear.