Context: Mast cells may be increased as a reactive mastocytosis in various hematologic disorders and malignant neoplasms, as well as in systemic mast cell disease (SMCD). There are no statistical differences in mast cell numbers in reactive mastocytosis and SMCD; however, SMCD usually reveals dyspoietic mast cells and other dyspoietic bone marrow elements. In addition, SMCD is frequently (45%) associated with myeloproliferative disorders (MPDs) (17%) and myelodysplastic syndromes (MDSs) (28%). Thus, it has been suggested that SMCD may represent one aspect of a hematologic disorder that involves multiple bone marrow lineages.
Objective: To perform a systematic evaluation of MPDs and MDSs without SMCD for dyspoietic mast cells.
Design: A total of 55 MPDs or MDSs were reviewed, including 20 cytogenetically proven chronic myeloid leukemias, 6 essential thrombocythemias, 2 polycythemia veras, 21 cytogenetically proven MDSs, and 6 chronic myelomonocytic leukemias. Cases of idiopathic myelofibrosis were not included due to lack of spicules. The bone marrow aspirates were reviewed for an increase in mast cells (1+ to 3+), dyspoietic features within mast cells (decreased cytoplasmic granularity, uneven granule distribution), and a predominance of fusiform mast cells.
Results: All cases, except 2 MDSs, had evaluable bone marrow spicules. Of interest, the MPDs were significantly more associated with increased and dyspoietic mast cells (57% and 61%, respectively) than were the MDSs (11% and 4%, respectively). The 2 polycythemia veras and 6 chronic myelomonocytic leukemias did not reveal increased or dyspoietic mast cells.
Conclusions: These findings indicate that MPDs (chronic myeloid leukemia and essential thrombocythemia) frequently contain neoplastic mast cells as the spectrum of abnormal bone marrow cells. This feature, in conjunction with other parameters, may possibly be useful in the differential diagnosis of MPDs and MDSs. Our findings, compared with the previously reported findings in SMCD, suggest that SMCD may be more closely related to MPDs than to MDSs.