Clinical characteristics and prognosis of nonleukemic myeloid sarcoma.

Myeloid sarcoma (MS) is an extramedullary mass that is composed of immature myeloid cells. The objectives of this study was to describe the frequency, clinical characteristics and the prognostic factors of patients with nonleukemic MS. Twenty-three cases of nonleukemic MS were recorded in the authors' institution between April 2006 and March 2012. Most of the patients received systemic antiacute myeloid leukemia chemotherapy and the overall response rate was 91.3%, and 56.5% patients experienced complete remission. The anticipated 3-year progression-free survival and overall survival rates are 23% and 41%, respectively. The prognostic impact of nonleukemic MS is unclear. The cytogenetic and molecular abnormalities of malignant cells may be the most important prognostic factor because these are not always available because of cost and technical reason. In this case, the remission state, Ki67 score of tumor cells and number and size of the lesions might act as independent prognostic factors; this finding requires further confirmation.