Localized residual leukaemia in bone marrow of extremities

This study aimed to confirm localized residual leukaemia in the abnormal expanded peripheral bone marrow (e-PBM) of the extremities using Tc-sulfur colloid imaging and bone marrow aspirations.

Whole-body bone marrow scintigraphy was performed in 420 adult and 48 childhood leukaemia patients using Tc-sulfur colloid (370 MBq). Central bone marrow (CBM) from the iliac crest and e-PBM from the proximal epiphyseal line of the tibia were aspirated at the time of routine examination and compared.

The expansion rate of the PBM in the non-remission stage of acute leukaemia was 73.1%, and it decreased to 38.4% in the complete remission stage. The most common site of PBM expansion was the epiphysis of the knee joint (74.5%). Cytological examination of the e-PBM at the complete remission stage revealed 30.9% localized residual leukaemia. The complete remission period (69+/-23 days) of PBM expansion was significantly greater than that of CBM depletion (43+/-31 days) (P<0.01). Localized residual leukaemia of the e-PBM could not be detected in the childhood acute leukaemia patients and in the patients without e-PBM. The difference in the relapse rate and time was statistically significant between patients with e-PBM (29.1%) and without e-PBM (3.5%) (P<0.01).

These findings suggest that induction chemotherapy does not always have a synchronous and parallel effect on CBM and PBM. The e-PBM is less sensitive to chemotherapy and can easily exist in localized residual leukaemia. The detection of residual leukaemia in the e-PBM by bone marrow scintigraphy is very important in the treatment of leukaemia.