From the Guidelines
Myeloid sarcoma is a rare malignant tumor consisting of immature myeloid cells occurring outside the bone marrow, also known as granulocytic sarcoma or chloroma, and represents an extramedullary manifestation of acute myeloid leukemia (AML) 1.
Definition and Characteristics
Myeloid sarcoma is a pathologic diagnosis for an extramedullary proliferation of blasts of one or more of the myeloid lineages that disrupts the normal architecture of the tissue in which it is found 1. It can affect various sites, including the skin, gastrointestinal tract, lymph nodes, and bone, and is often associated with AML, either concurrently or preceding the appearance of blood or bone marrow disease 1.
Diagnosis and Treatment
Diagnosis requires tissue biopsy with immunohistochemistry showing myeloid markers such as CD33, CD34, MPO, and lysozyme 1. Treatment typically involves systemic chemotherapy similar to AML protocols, using induction regimens containing cytarabine and an anthracycline (such as daunorubicin or idarubicin) 1. Local radiation therapy (20-30 Gy) may be added for localized disease, particularly for symptomatic lesions or those causing organ compression. Allogeneic hematopoietic stem cell transplantation should be considered for eligible patients to improve long-term outcomes.
Prognosis and Outcomes
Prognosis depends on associated bone marrow disease, cytogenetics, and response to initial therapy 1. Prompt diagnosis and treatment are essential as myeloid sarcoma often precedes or coincides with bone marrow involvement. The disease can affect various sites, including skin, lymph nodes, gastrointestinal tract, and central nervous system, with symptoms depending on the location and size of the tumor.
Some key points to consider:
- Myeloid sarcoma is a rare manifestation of AML, characterized by the occurrence of one or more myeloid tumor masses at an extramedullary site 1.
- Intensive AML-specific chemotherapy stratified according to general AML risk factors is recommended for all patients with myeloid sarcoma 1.
- Local irradiation may be considered, but prospective studies are lacking due to the rarity of these manifestations 1.
From the Research
Definition and Characteristics of Myeloid Sarcoma
- Myeloid sarcoma (MS) is a rare tumor mass of myeloid blasts that can disseminate to any one or multiple anatomical sites, with or without bone marrow involvement 2, 3, 4.
- It is a high-grade, hematological malignancy defined as an extramedullary tumor mass of myeloid blasts with or without maturation that effaces tissue architecture 4.
- MS is a highly heterogeneous condition that represents a variety of myeloid neoplasms, making it challenging to understand and manage 4.
Clinical Manifestations and Diagnosis
- MS can present as a palpable lump or mass in various organs, including the breast, and can be diagnosed through tumor biopsy and bone marrow evaluation 5.
- Immunohistochemistry (IHC) and genetic profiling can help identify the tumor cells and detect recurrent genetic abnormalities associated with MS 4, 5.
- Diagnosis requires a high suspicion index, careful inquiry of the patient's medical history, and combination of information from the patient's medical history with tumor biopsy 5.
Treatment and Prognosis
- Treatment of MS is generally similar to that of acute myeloid leukemia (AML), including induction chemotherapy, hematopoietic stem cell transplantation (HSCT), and ablative radiotherapy 2, 3, 4.
- Novel targeted therapies and maintenance therapy with drugs such as 5-azacytidine may also be beneficial in managing MS 6.
- Prognosis is generally poor, especially in patients with extramedullary relapse after HSCT, but prompt treatment and individualized therapeutic approaches can improve outcomes 3, 5.