Myelosarkom
Myeloid sarcomas, also called granulocytic sarcomas, chloromas, or extramedullary myeloid tumors, are rare extramedullary masses comprised of myeloid precursor cells. These tumors represent a unique presentation of acute myeloid leukemia (AML), whether in isolation to, preceding, or simultaneous with bone marrow and peripheral blood disease.
Different from leukemic infiltrates, myeloid sarcomas characteristically efface the involved tissue architecture, and are recognized as a distinct entity in the WHO classification of tumors of hematopoietic and lymphoid tissues.
Epidemiology
It is more commonly seen is in children, with ~60% occurring in individuals less than 15 years of age. There is no recognized gender predilection.
Myeloid sarcoma may develop during the course of a hematologic disorder but is seen to precede the disorder in 35% of cases.
Pathology
Myeloid sarcoma lesions are composed of immature myeloid elements and therefore represent focal accumulations of leukemic cells. In contrast to its associated entities, the lesion takes the form of a solid soft tissue mass that effaces the underlying involved tissue architecture (cf. leukemic infiltrates).
They can occur with or without relation to other forms of myeloid disorders :
- de novo: with no prior history of myeloproliferative and myelodysplastic disorders
- simultaneously with a myeloproliferative and myelodysplastic disorder: concomitant peripheral blood and marrow involvement
- as a relapse of a treated myeloproliferative and myelodysplastic disorder
- as a form of blast transformation from a prior myeloproliferative neoplasm
Location
Extramedullary involvement is a defining feature.
Almost any tissue can be affected, with skin and bone being the commonest. They have been reported in the skull, face, orbit, and paranasal sinuses. Lesions have been reported in the tonsils, oral and nasal cavities and within the lacrimal, thyroid and salivary glands. The central nervous system can also be affected.
Associations
As described in the World Health Organization classification, myeloid sarcoma is considered a unique presentation, not a subtype, of acute myeloid leukemia (AML) .
As with other forms of acute myeloid leukemia, myeloid sarcoma can evolve from myelodysplastic syndromes as well as the myeloproliferative neoplasms:
Radiographic features
Exact imaging features will depend on the location and involved organ:
- CNS manifestations of granulocytic sarcoma
- spinal leukemia
- head and neck manifestations of granulocytic sarcoma
- skeletal manifestations of granulocytic sarcoma
- abdominal manifestations of granulocytic sarcoma
- thoracic manifestation of granulocytic sarcoma
History and etymology
- first described by A Burns in 1811
- termed "chloroma" in 1853 by King due to typical forms have a green color from high levels of myeloperoxidase in immature cells
- renamed as "granulocytic sarcoma" in 1966 by Rappaport when it was demonstrated that an estimated 30% of cells do not contain myeloperoxidase, therefore, a significant proportion of cells are not green in color
- recently preferred to be termed "myeloid sarcoma" , as several associated types of myeloid leukemia are defined by little to no granulocytic differentiation
Siehe auch:
- Akute myeloische Leukämie
- Myelodysplastisches Syndrom
- epidurales spinales Myelosarkom
- zerebrales Myelosarkom
- intradurale spinale Beteiligung bei Leukämie
- Myeloproliferative Neoplasien (MPN)
und weiter:
Assoziationen und Differentialdiagnosen zu Myelosarkom:
