FLOCK cluster analysis of mast cell event clustering by high-sensitivity flow cytometry predicts systemic mastocytosis.
OBJECTIVE
In our high-sensitivity flow cytometric approach for systemic mastocytosis (SM), we identified mast cell event clustering as a new diagnostic criterion for the disease.


METHODS
To objectively characterize mast cell gated event distributions, we performed cluster analysis using FLOCK, a computational approach to identify cell subsets in multidimensional flow cytometry data in an unbiased, automated fashion.


RESULTS
FLOCK identified discrete mast cell populations in most cases of SM (56/75 [75%]) but only a minority of non-SM cases (17/124 [14%]). FLOCK-identified mast cell populations accounted for 2.46% of total cells on average in SM cases and 0.09% of total cells on average in non-SM cases (P < .0001) and were predictive of SM, with a sensitivity of 75%, a specificity of 86%, a positive predictive value of 76%, and a negative predictive value of 85%.


CONCLUSIONS
FLOCK analysis provides useful diagnostic information for evaluating patients with suspected SM, and may be useful for the analysis of other hematopoietic neoplasms.
From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA. ddorfman@partners.org.
David M
DM
Dorfman
From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
Charlotte D
CD
LaPlante
From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
Olga
O
Pozdnyakova
From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
Betty
B
Li
D016000:Cluster Analysis; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping; D008407:Mast Cells / Q000276:immunology*; D034721:Mastocytosis, Systemic / Q000175:diagnosis* / Q000276:immunology; D012680:Sensitivity and Specificity
Cluster analysis; Flow cytometry; Systemic mastocytosis