Myeloid sarcoma as the initial presentation of chronic myelogenous leukemia, medullary chronic phase in era of tyrosine kinase inhibitors: A report of 11 cases
Authors: Zi Chen, Wei Wang, Amy Rich, Guilin Tang, Shimin Hu
Journal: American Journal of Hematology (2015)

Myeloid sarcoma (MS) is a tumor mass consisting of myeloid blasts occurring at an anatomical site other than bone marrow (BM). MS can arise in the setting of chronic myelogenous leukemia (CML), especially in accelerated phase or blast phase (BP) in BM and peripheral blood (PB). Occasionally, MS can arise in CML, chronic phase (CP) in BM and PB (medullary CP). Very rarely, MS presents as the initial presentation of CML, medullary CP. Until now, only six cases of MS as the initial presentation of CML in medullary CP are reported 1-6. Here, we report 11 cases of MS as the initial presentation of CML in medullary CP diagnosed from January 2000 to December 2014 (Table 1). There were nine men and two women with a median age of 51 years (range: 23–73). All patients presented with symptoms related to local suppression and/or invasion by MS. The neoplastic myeloid cells of sarcoma in all cases showed blastic or immature morphology. After the diagnosis of MS, further BM and PB examinations, including cytogenetics and molecular analyses, confirmed the diagnosis of CML, medullary CP. All patients received treatment of tyrosine kinase inhibitors (TKI), and three underwent allogeneic hematopoietic stem cell transplantation (Allo-HSCT). One patient (#6) developed medullary BP 39 months after the initial diagnosis of MS. After a median follow-up of 22 months (range: 4–147), four patients died, three from the progression of disease, and one from graft-versus-host disease after Allo-HSCT. Of the seven living patients, one patient achieved cytogenetic remission, three major molecular remission and three complete molecular remission. The median overall survival (OS) is 40 months (Fig 1). Overall survival of CML patients with myeloid sarcoma as the initial presentation. The intriguing part of our study was that the prognosis of this cohort of 11 patients was not as poor as expected. The emergence of MS is considered one sign of BP in CML, and suggests a very poor prognosis. In the pre-TKI era, the OS of CML patients with MS was 3–6 months 7, 8, similar to the OS of CML in medullary BP, which was about 4 months 9. In the TKI era, the OS of CML in medullary BP is 6–11 months 9, 10, and the OS of CML patients with MS is not known. MS as the initial presentation of CML-CP may be a unique subset of CML and the prognosis is unclear due to the rarity of this disease. In our cohort of MS diagnosed in the era of TKIs, the median OS is 40 months, which is significantly better than that of CML in medullary BP in the era of TKIs. Although the number of cases is limited, it seems that the prognosis of MS as the initial presentation of CML-CP is different from CML-BP. There are two possible explanations for the better outcome of CML patients with MS as the initial presentation than that of patients with CML in medullary BP. MS and medullary BP, or MS as the initial presentation and as late presentation, have different biology and thus different prognoses. MS as the initial presentation of CML may not necessarily have treatment resistance and disease progression as indicated by MS or BP as the late sequela of CML. Zi Chen1,2, Wei Wang1, Amy Rich1, Guilin Tang1, Shimin Hu1* 1Department of Hematopathology, the University of Texas MD Anderson Cancer Center, Houston, Texas;2Department of Hematology, Huashan Hospital, Fudan University, Shanghai, China