KIT D816V Positive Acute Mast Cell Leukemia Associated with Normal Karyotype Acute Myeloid Leukemia

Table 3

Clinical and laboratory features in our patient as compared to those observed in patients with MCL or MML, as schematized by Valent et al. in 2014 [9].

	Mast cell leukemia (MCL)	Myelomastocytic leukemia (MML)	This case (MCL-AML)
Clinical features
Skin lesions	Present in a subset of patients	Absent	Yes (maculopapular rash)
Spleen involvement/splenomegaly	Found in a subset of patients	Usually present at diagnosis	Yes (13 cm; splenic nodules)
Liver involvement/hepatomegaly, ascites	Often found	Usually not found	Yes (18.5 cm; cholestasis; ascites)
MC mediators-related symptoms	Frequent	Frequent	Yes (flushing; diarrhea)
Peripheral blood findings
Serum tryptase (μg/L)	Markedly elevated (usually >200; often >500)	Moderately elevated (usually <100; often <50)	184 μg/L
Circulating MC	Present in a subset of patients	Present in a subset of patients	Yes (CM: 20%); FCM: 21% MCP
Circulating myeloblasts	No (except MCL-AHN)	Present in a subset of patients	Yes (CM: 6%); FCM: 3% MPC
Bone marrow findings
Underlying non-MC myeloid neoplasms	No (except MCL-AHN)	Yes	AML (concomitant diagnosis)
Increased myeloblasts	No (except MCL-AHN)	Almost always seen	Yes (CM: 24% myeloblasts + 17% promyelocytes); FCM: 12% MPC + 34% promyelocytes
MC clusters and sheets in BM biopsy	Yes	No	Yes
Diffuse MC infiltrate in the BM biopsy	Yes	Yes	Yes
MC in BM smears	≥20%	≥10%	Yes (CM: 16%); FCM: 5% MCP + 13% MC
Karyotype	Normal or abnormal with a few lesions (except MCL-AHN)	Usually complex	Normal
CD25+ MC	Yes	No	Yes
KIT D816V or other codon 816 mutation	Present	Not found	Yes (BM mast cells, CD34+ precursors and other myeloid cells)
KIT mutations in non-816-codons	Found in a subset of patients	Found in a subset of patients	Not investigated

AHN, associated hematological neoplasm; AML, acute myeloid leukemia; BM, bone marrow; CM, cytomorphology; FCM, flow cytometry; MC, mast cells; MCL, mast cell leukemia; MCL-AHN, mast cell leukemia with associated hematological neoplasm; MCP, mast cell precursors; MML, myelomastocytic leukemia; MPC, myeloid precursor cells. Past history of uninvestigated maculopapular skin lesions and flushing episodes; maculopapular rash at the diagnosis (skin biopsy not performed). In MML, the karyotype usually reflects the nature of the underlying disease, whereas no recurrent chromosome abnormalities are known for patients with MCL.