Extramedullary leukemia

And uncommon presentation of AML.

Usually reflects systemic disease.

Rarely presents without evidence overt hematological disease, and if untreated, virtually all will develop systemic disease.

Can present in a variety of forms including myeloid sarcoma, also termed granulocytic sarcoma, chloroma, or myeloblastoma, leukemia cutis, and CNS disease.

The prognosis impact is controversial.

Extramedullary leukemic disease is correlated with specific AML phenotypes and chromosomal abnormalities.

The three major forms are myeloid sarcoma, CNS disease, and leukemia cutis.

CNS involvement with AML is less than 5%, and probably in the range of 2-3% at presentation or relapse.

Leukemia cutis is relatively rare and is estimated to occur in 3% of cases of AML.

Both CNS involvement and leukemia cutis are more frequent in myelomonocytic and monoblastic phenotypes.

Leukemia cutis may be associated with abnormalities of chromosome 8.

Leukemia cutis can occur at presentation of AML, after diagnosis, or at the time of relapse.

Leukemia cutis is very rare in the absence of systemic disease and its appearance without evidence of systemic disease almost always portends later development of systemic bone marrow involvement.

Leukemia cutis manifests primarily as a violaceous papular rash.

Leukemia cutis may be associated with shorter remissions in AML, however in patients who underwent allogeneic transplant the risk of relapse was not higher in patients with leukemia cutis, but was associated with a higher rate of extramedullary relapse.

Leukemia cutis overall is considered a more aggressive variant of AML and an indicator of poor prognosis.

Leukemia cutis is considered to be evidence of systemic disease and is treated with standard systemic chemotherapy.

The incidence of myeloid sarcoma is estimated at 2-9% in most series.

Common sites of involvement of extramedullary disease include soft tissues, periosteum, bone, and lymph nodes.

Myeloid sarcoma can present at, or after diagnosis or can be a manifestation of relapsed disease of AML.

Myeloid sarcoma presentation is rare in the absence of systemic leukemia, and most patients will develop detectable systemic disease in the absence of treatment.

Myeloid sarcoma may be seen in myelodysplastic syndromes, myeloproliferative disorders, and CML.

FAB M4 and M5 subtypes are most commonly associated with extramedullary AML.

More than 40% of patients with myeloid sarcoma have monoblastic or myelomonocytic morphologic AML.

Myeloid sarcoma associated with higher initial WBC counts.

Abnormal chromosome abnormalities with myeloid sarcoma include t(8;21), inv(16), 11q23, NPM1, and FLT3 internal duplication mutations.

The neural cell adhesion molecule CD56 is expressed in a significant number of myeloid sarcoma lesions.

MLL gene mutation, specifically 11q23 abnormality, has a poor prognosis and is linked to extramedullary involvement.

Myeloid sarcoma often occurs with bone marrow involvement, and standard treatment should be induction chemotherapy for AML.

Leave a Reply

Your email address will not be published. Required fields are marked *