Table 3.
Characteristics of JMML-like NS/MPD in children
| Characteristic | JMML-like | JMML |
|---|---|---|
| NS status | NS | No NS |
| Age at onset | <2 mo | Median, 1.8 y |
| Leukocytosis | Present | Present |
| Monocytosis | Present | Present |
| Hepatosplenomegaly | Present | Present |
| Myelopoiesis | Polyclonal | Clonal |
| Cytogenetics | Normal | Abnormal in 35% |
| PTPN11 mutation | 90% (germ line) | 35% (somatic) |
| Most common substitution | T73I | E76K |
| Biological effect | Moderate gain of function | Strong gain of function |
| Outcome | Spontaneous regression | Fatal without transplantation |