[1216] Expression of 2D7, a Unique Marker of Basophils in Myeloproliferative Neoplasms.

Angela Arredondo, Charay Jennings, Uma Sundram, Zhi Shun Lu, Tracy George. Stanford University, CA

Background: 2D7 has been reported to be a specific marker for basophils in paraffin-embedded bone marrow sections. Myeloproliferative neoplasms such as chronic myelogenous leukemia (CML) are characterized by increased basophils either in the bone marrow or in the peripheral blood. In some reports, the degree of basophilia is an independent predictor of a less favorable clinical outcome as the number of basophils often increases during the acceleration phase of CML. Basophils can also be difficult to distinguish from atypical mast cells based on morphology. Given the prognostic importance of basophils in some diseases, a sensitive and specific immunohistochemical marker such as 2D7 would be helpful in ensuring an accurate basophil count and in distinguishing basophils from atypical mast cells.
Design: In this study, we sought to confirm the specificity of 2D7 as a basophil marker in paraffin embedded bone marrow biopsies from patients with myeloproliferative neoplasms, including systemic mastocytosis and myelomastocytic leukemia, (n=37) in contrast with myelodysplastic syndromes (MDS, n=16), myelodysplastic/ myeloproliferative neoplasms (MDS/MPN, n=6), myeloid neoplasms with eosinophilia (n=1), and reactive/normal marrows (n=9). We also examined skin biopsies from patients with cutaneous mastocytosis (n=12). Standard immunohistochemical techniques were performed and mean numbers of 2D7+ cells were quantified per 1mm2 on whole sections and tissue microarrays.
Results: 2D7+ bone marrow cells were increased in CML, polycythemia vera, chronic eosinophilic leukemia, and myeloid neoplasm with eosinophilia compared with normal/reactive marrow, MDS, MDS/MPN, mastocytosis, essential thrombocythemia, and primary myelofibrosis. 2D7 stained positively in basophils but not in mast cells in cutaneous and systemic mastocytosis cases.
Conclusions: 2D7 is a specific marker for basophils which is found in increased numbers in paraffin embedded bone marrow biopsies in CML and a subset of myeloproliferative neoplasms. 2D7 allows for definitive separation of basophils from atypical mast cells in mastocytosis.
Category: Hematopathology

Monday, February 28, 2011 1:00 PM

Poster Session II # 180, Monday Afternoon


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