A case study published recently in The American Journal of Pathology describes a patient with a history of acute myeloid leukemia (AML) who developed systemic mastocytosis (SM) after undergoing a bone marrow transplantation.
The researchers sought to establish whether the development of SM in this individual represented donor-driven disease or SM with an associated myeloid neoplasm.
SM has been characterized as exhibiting a variable presentation, which can range from indolent SM to aggressive SM. SM with an associated myeloid neoplasm, which is another form of the disorder, can occur either concomitantly with the neoplasm or within an interval of a myeloid neoplasm, and should fulfill the diagnostic criteria of both possibilities.
The patient depicted, who had a history of AML with KMT2A(11q23) amplification, had initially received an allogeneic hematopoietic stem cell transplantation from a matched sibling donor. At one year following the original transplant, the patient developed isolated central nervous system relapse, along with evidence of molecular bone marrow relapse. A second allogeneic transplantation was performed in the patient, with a matched unrelated donor involved this time.
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At a bone marrow biopsy performed 100 days after the second transplantation, the results were negative for involvement of AML. In fact, findings from chimerism genetic testing, which the patient underwent to monitor the success of the transplant, demonstrated “evidence of total engraftment with 100% donor cells.”
The use of fluorescence in situ hybridization analysis showed no evidence of KMT2A amplification. Morphological examination of the bone marrow biopsy, however, revealed involvement by SM “with multiple dense aggregates of CD117 and tryptase[-]positive mast cells showing spindled cell morphology.”
Of note, the patient’s mast cells were positive for CD25, with negative expression of CD2 and CD30 reported. Polymerase chain reaction exploration of peripheral blood was unable to detect any indication of the KIT mutation. The patient’s serum tryptase levels were elevated, however.
This case highlights a rare situation of SM occurring in a patient in the setting of AML remission following a bone marrow transplantation “and represents a diagnostic challenge.”
Although the development of SM in an individual with a prior history of AML “suggests the possibility of [SM] with an associated myeloid neoplasm, some other features[,] including the complete remission and total engraftment of the post transplantation bone marrow with 100% donor cells, raise the possibility of a donor[-]driven disease,” the authors concluded.
