Granulocytic sarcoma (GS),
myeloid sarcoma or chloroma is defined as a focal aggregation of extramedullary myeloid precursor cells associated with leukemia.
GS is a mass of blast cells outside the bone marrow; the term “chloroma” was first used in 1853 to refer to the green color of the tumor caused by high content of myeloperoxidase.
because up to 30% of these tumors can be white,
Rappaport renamed them granulocytic sarcoma in 1966 
all these forms are uncommon,
usually associated with medullary leukemia.
it also can be found in association with other myeloproliferative disorders including myeloid metaplasia,
and chronic eosinophilic leukemia .
Granulocytic sarcoma can affect any part of the body but orbital,
facial and abdominal affection is frequently reported.
Bone affection is also common.
The pathogenesis of bone involvement has been postulated to be via trans–haversian canal migration of leukemia cells from the bone marrow to the periosteum and dura .
central nervous system involvement has been theorized to occur via perivascular or perineural routes from direct dural extension or through capillary migration .
Granulocytic sarcoma in the gastrointestinal or genitourinary system may arise de novo from nests of hematopoietic cells.
Granulocytic sarcoma usually presented in patients had a history of AML.
But it could be the first presentation of the disease,
even in these cases; the patients developed AML within 2 years.
Granulocytic sarcoma presented clinically with variable symptoms and signs related to either the mass itself or disturbance of the organ which harbored the mass .
Management of granulocytic sarcoma consists mainly of systemic chemotherapy for the underlying leukemia,
and usually has good therapeutic results. Surgical debridement or radiation therapy is needed in when urgent decompression is needed,
or if the lesion is refractory to systemic chemotherapy.
The radiological knowledge about the diagnostic criteria of the granulocytic sarcoma is so important and has a great impaction in the proper management.
As the prompt diagnosis will facilitate appropriate treatment and disease control,
and the misdiagnosis of this potentially curable disease would have lead to unnecessary surgery and increased morbidity to the patient.
granulocytic sarcoma in pediatrics usually occurs as extramedullary manifestation of acute myeloid leukemia.
The clinical presentations are variable and may include compressive or obstructive symptoms.
Despite the variable nature of the disease,
there are a few features,
particularly of central nervous system granulocytic sarcoma,
that may help to distinguish these lesions from other common complications of leukemia.
Signs strongly suggestive of granulocytic sarcoma are multiple,
solid masses occurring at different sites and time points during the course of disease in a patient with either acute myeloid leukemia or myeloproliferativ or myelodysplastic disorders.
So the radiologist should be aware of chloromas when evaluating a local mass of unknown etiology,
especially in patients with a known history of AML.
Knowledge of this diagnostic possibility can expedite treatment for the patient and eliminate unnecessary procedures.