Myelomastocytic leukemia: evidence for the origin of mast cells from the leukemic clone and eradication by allogeneic stem cell transplantation.
OBJECTIVE
Myelomastocytic leukemia is a term used for patients with advanced myeloid neoplasms, in whom elevated numbers of immature atypical mast cells are found, but criteria for a primary mast cell disease are not met. The origin of mast cells in these patients is presently unknown.


METHODS
We have analyzed clonality of mast cells in an 18-year-old patient suffering from acute myeloid leukemia with a complex karyotype including a t(8;21) and mastocytic transformation with a huge increase in immature mast cells and elevated serum tryptase level, but no evidence for a primary mast cell disease/mastocytosis.


RESULTS
As assessed by in situ fluorescence hybridization combined with tryptase staining, both the tryptase-negative blast cells and the tryptase-positive mast cells were found to contain the t(8;21)-specific AML1/ETO fusion gene. Myeloablative stem cell transplantation resulted in complete remission with consecutive disappearance of AML1/ETO transcripts, decrease of serum tryptase to normal range, and disappearance of neoplastic mast cells.


CONCLUSIONS
These data suggest that mast cells directly derive from the leukemic clone in patients with myelomastocytic leukemia.
Sperr
Wolfgang R
WR
Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Austria. wolfgang.r.sperr@meduniwien.ac.at
Drach
Johannes
J
Hauswirth
Alexander W
AW
Ackermann
Jutta
J
Mitterbauer
Margit
M
Mitterbauer
Gerlinde
G
Foedinger
Manuela
M
Fonatsch
Christa
C
Simonitsch-Klupp
Ingrid
I
Kalhs
Peter
P
Valent
Peter
P
D000293:Adolescent; D018952:Antigens, CD34 / Q000096:biosynthesis; D014408:Biomarkers, Tumor; D001854:Bone Marrow Cells / Q000378:metabolism; D018801:CD2 Antigens / Q000096:biosynthesis; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D005434:Flow Cytometry; D042381:Granulocyte Precursor Cells / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D015470:Leukemia, Myeloid, Acute / Q000175:diagnosis* / Q000235:genetics* / Q000473:pathology; D008297:Male; D008407:Mast Cells / Q000166:cytology* / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D012697:Serine Endopeptidases / Q000097:blood / Q000378:metabolism; D033581:Stem Cell Transplantation / Q000379:methods*; D014178:Translocation, Genetic; D014184:Transplantation, Homologous; D053802:Tryptases
D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D018801:CD2 Antigens; D015375:Receptors, Interleukin-2; D019009:Proto-Oncogene Proteins c-kit; D012697:Serine Endopeptidases; D053802:Tryptases