Jacobs Journal of Clinical Case Reports

Isolated Mediastinal Myeloid Sarcoma: A Rare Presentation of Extramedullary Leukemic Tumor

*Carol Portlock
Department Of Medicine, Memorial Sloan Kettering Cancer Center, United States

*Corresponding Author:
Carol Portlock
Department Of Medicine, Memorial Sloan Kettering Cancer Center, United States
Email:portlocc@mskcc.org

Published on: 2018-05-28

Abstract

Myeloid sarcoma is a rare solid tumor consisting of myeloid blasts that proliferate in any extramedullary site. It can present before, concurrent with or after the diagnosis of acute myeloid leukemia [AML] or other myeloproliferative disorders. The most common sites include skin, gum, lymph nodes, soft tissue, periosteum, and bone. Here, we present a 66-year-old male with a history of bladder cancer and colon cancer who presented with intermittent fever, chest heaviness, dry cough and dyspnea on exertion. CT scan of the chest showed a bulky mediastinal mass. Biopsy and immunohistochemical studies confirmed the diagnosis of myeloid sarcoma. Peripheral blood smear did not show any blasts and bone marrow biopsy was normal. The patient received AML-directed chemotherapy followed by radiation therapy and allogeneic hematopoietic stem cell transplantation.

Keywords

Myeloid sarcoma; Mediastinal Mass; PET; AML

Introduction

Myeloid sarcoma is included as one of the subgroups of acute leukemia in the WHO classification and is most often found either concurrently or following a previously recognized AML. Less often it may occur as an isolated leukemic tumor or precede the appearance of blood or bone marrow disease [1]. The incidence of MS in AML is less than 1% and the involvement of the mediastinum is extremely rare [2-4]. Skin, gum, lymph nodes, soft tissue, periosteum, and bone are the most common involved locations [5]. The definitive diagnosis is usually based on immunohistochemistry. The use of only four markers (MPO, CD68, Lysozyme and CD34) has been proposed to distinguish the more common variants of myeloid sarcomas [6]. Molecular and cytogenetic studies are usually performed because the results have prognostic and therapeutic implications. The recommended treatment is AML-directed chemotherapeutic protocols. The role of Radiation therapy and hematopoietic stem cell transplantation has not been clearly established. Complete remission rates for isolated MS treated with AML-based induction regimens are comparable to those of AML without MS but with similar prognostic features, and a disease -free survival from 3.5 to 16 years has been reported [7]. We describe a patient with a bulky mediastinal myeloid sarcoma. We discuss the literature pertaining to clinicopathological features in MS, PET imaging and treatment options.