Granulocytic Sarcoma, A Single-Institution Survey of Clinical Presentation and Trajectory
Authors: Sadrzadeh Hossein , Deysher Nathan , Jamali Layli , Brunner Andrew M. , Drapkin Benjamin J. , Ballen Karen K. , Attar Eyal C. , Amrein Philip C. , McAfee Steven L. , Fathi Amir T 
Published: October 2019

Abstract
Abstract 1041

Introduction
Granulocytic Sarcoma (GS), also known as chloroma or myeloblastoma, is a rare neoplasm composed of immature myeloid cells occurring in any extramedullary organ, most commonly in the lymph node and soft tissue. It can occur as an isolated lesion, or in conjunction with a diagnosis of acute myeloid leukemia (AML), myeloproliferative disorder (MPD) or myelodysplastic syndrome (MDS). GS has been generally associated with more aggressive disease and a poor prognosis. Although it has been described in the literature in small case series, the clinical characteristics and prognosis of patients with GS associated with AML, MDS, MPD or as an isolated lesion have not been thoroughly described. We therefore studied our institutional experience of granulocytic sarcoma to gain further insight into the clinical features and associations of this disease.

Methods
We conducted a retrospective medical record review of patients who presented with GS to Massachusetts General Hospital from 1994 through 2011. In total, 35 patients with GS were identified. Kaplan Meier method was used to estimate overall survival (OS). OS was defined as the duration from the time of diagnosis of GS to date of death; patients still alive at the time of analysis were censored. Patients were categorized into three groups for analysis depending on the presence of bone marrow disease: primary (isolated) GS, GS associated with AML, and GS associated with MDS or MPD.

Result
Of 35 patients with GS, 20 (57%) were associated with a diagnosis of AML, 10 (29%) presented with either MDS or MPD, and 5 (14%) presented with primary GS. Of the AML-associated GS, 13 occurred concurrently with AML at diagnosis and 7 presented as AML relapse. Of the 10 cases of GS with either MDS or MPD, one patient presented with MDS and 9 with MPD. The median age of all patients was 57 years old; 19 of 35 patients were female. Median white blood count (WBC) was 4.6 (th/cmm) (IQR 3.5–8.8) for patients with AML-associated GS and 20.2 (th/cmm) (IQR 9.7–61) for those with MDS/MPD-associated GS. One year survival was 10% (95% CI 0.5 – 35.8%) in MDS/MPD associated GS, 49.5% (95% CI 26.5 – 68.9%) in AML associated GS, and 60% (95% CI 12.6 to 88.2%) in primary GS. The most common area of involvement in patients with AML-associated GS was the nervous system (22%). In contrast, among patients with MPD/MDS-associated GS, the most commonly involved site was bone (45%) (Table 1). 63% of all patients had one site of involvement with GS at presentation. The most common presenting symptom was pain either caused by a mass or lymphadenopathy. Cytogenetics were normal for the majority of patients. Interestingly, however, one AML patient and one patient with primary GS presented with a 9;22 translocation, two AML presented with other cytogenetic abnormalities involving chromosome 9 (t(9;11)(p22;q23) & add(9)(q34)), and three others, including one with primary GS, displayed abnormalities at chromosome 11, specifically 11q23 (Table 2).

Conclusions
With this study, we provide a single institution experience of granulocytic sarcoma, a rare manifestation of myeloid neoplasms. Interestingly, we found variable presentation with different patterns of site involvement and white blood counts in patients with GS associated with AML and in those with GS associated with MPD/MDS. Additionally, certain karyotypic abnormalities were over-represented in patients with GS, including t(9;22) and translocations involving chromosome 11q23. Finally, in our small series, patients with a diagnosis of GS associated with MPD/MDS had worsened outcomes compared to those with AML-associated GS or primary GS. Larger, prospective studies are needed to better and more fully assess outcomes in these patients.

Disclosures:
No relevant conflicts of interest to declare.