Table 4.
Cytomorphologic criteria of mast cell (MC) types detected in the BM smear in patients with MCL, other variants of systemic mastocytosis (SM) or myelomastocytic leukemia (MML)
| Type of MC | Criteria | Typically found in patients with |
||||
|---|---|---|---|---|---|---|
| MML | Acute MCL | Chronic MCL | ASM | ISM | ||
| Typical MC | Round cells, well granulated, central round nucleus | − | − | −/+a | − | −/+a |
| Atypical MC type I | (a) Elongated surface projections, often spindle-shaped cells, (b) hypogranulated cytoplasm, (c) oval decentralized nucleus. → 2 or 3 of a/b/c | − | − | +/− | +/− | + |
| Atypical MC type II = promastocyte | Mostly immature, with bi- or multi-lobed nuclei | + | + | +/− | +/− | −/+ |
| Metachromatic blast | Myeloblast with few or several metachromatic granules | + | + | −/+ | −/+ | − |
aIn patients with well-differentiated SM (WDSM), mast cells are mostly round and well-granulated cells. In some of these patients, the disease may progress to chronic MCL with round MCs.
MC(s), mast cell(s); ASM, aggressive SM; ISM, indolent SM.