Localized lymphoid relapse in the pancreas following allogeneic hematopoietic stem cell transplant for chronic myelogenous leukemia.

The incidence of isolated extramedullary disease (EMD) following allogeneic hematopoietic stem cell transplant (allo-HSCT) for chronic myelogenous leukemia (CML) is not fully known. One review found the incidence of isolated myeloid EMD, or granulocytic sarcoma (GS), in an allo-HSCT treated CML/myelodysplastic subgroup to be just 0.22%. The incidence of lymphoid EMD in similar patients is extremely rare with only two cases reported in the literature. While the etiology of EMD in the post-transplant setting is not entirely clear, there may be inefficacy of immune surveillance function outside of the bone marrow cavity. Isolated CML GS following allo-HSCT carries a median interval to bone marrow relapse between 7 and 10 months and a median survival of 12 months. Less is known about lymphoid EMD. The treatment in these cases is ill defined with modalities ranging from involved field radiation to second allo-HSCT. We present a case of isolated pancreatic lymphoid EMD diagnosed 15 months after allo-HSCT for CML. Our patient was also treated with withdrawal of his immunosuppressive regimen. Unfortunately, at just over 4 months following pancreatic resection, he developed systemic relapse and died. While EMD can occur anywhere in the body, CML associated pancreatic EMD is not previously reported.