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myeloid sarcoma (extramedullary myeloid tumor, granulocytic sarcoma, chloroma)
Pathology:
1) solid tumor of myeloblasts or immature myeloid cells in an extramedullary site or in bone
2) granulocytic form also contains neutrophils
3) less common monoblastic form
4) tumors of 3 lineages: myeloblasts, erythroblasts & megakaryocytes
Genetics:
1) chromosomal translocation: t(8;21)(q22;q22)
2) chromosomal inversion: inv(16)(p13q22)
3) chromosomal translocation: t(16;16)(p13;q22)
4) monoblastic form: translocations involving 11q23
Clinical manifestations:
1) may precede or occur concurrently with:
a) acute myeloid leukemia (AML)
b) chronic myeloid leukemia
c) myelodysplastic syndrome
d) other myeloproliferative disorders
2) may be interval of months to years between occurrence of myeloid sarcoma & AML
3) may be initial manifestation of relapse in previously treated AML in remission
4) sites of occurrence
a) subperiosteal bone of skull, paranasal sinuses, sternum, ribs, vertebrae, pelvis
b) lymph nodes
c) skin
Laboratory:
1) immunophenotyping by flow cytometry or immunohistochemistry
a) myelomonocytic antigens
b) myeloperoxidase
c) chloroacetate esterase
2) expression of myeloid-associated antigens
a) CD13
b) CD33
c) CD117
d) CD43 (most)
3) monoblastic form may express
a) CD14
b) CD116
c) CD11c
d) CD68 (generally)
4) CD61 NOT expressed (used to rule out myeloid sarcoma)
Differential diagnosis:
1) non Hodgkin's lymphoma, lymphoblastic type
2) Burkitt lymphoma
3) large cell lymphoma
4) small round cell tumors, especially in children
a) neuroblastoma
b) rhabdomyosarcoma
c) Ewing's sarcoma
d) medulloblastoma
Management:
1) when occurring concurrently with leukemia, prognosis is that of underlying leukemia
2) as an isolated lesion, radiation therapy may be curative
Interactions
disease interactions
General
hematologic malignancy (hematopoietic malignancy, hematologic cancer)
myeloproliferative disorder
sarcoma
Properties
SITE: skin
orbital cavity
paranasal sinus
bone
thoracic wall
breast
gastrointestinal system
respiratory system
urogenital system
central nervous system
peripheral nervous system
lymph node
CELL-OF-ORIGIN: myeloblast
monoblast
References
WHO Classifiation of Tumors, Pathology & Genetics,
Tumores of Haematopoietic and Lymphoid Tissues, Jaffe et al (eds)
IARC Press, Lyon 2001