Evaluation of neoplastic human mast cells by tryptase-immunoelectron microscopy.
OBJECTIVE
To analyse and characterize the ultrastructural morphology of normal tissue mast cells (MC) and neoplastic bone marrow MC.


METHODS
We have examined the ultrastructure and cytomorphological features of MC derived from cord blood cells, neoplastic bone marrow MC in patients with systemic mastocytosis (SM, n = 4), myelomastocytic leukaemia (MML, n = 2), mast cell leukaemia (MCL, n = 2) and tryptase-positive acute myeloid leukaemia (AML, n = 4).


RESULTS
Based on their ultrastructure and morphology, four distinct cell types could be delineated: (i) mature well-granulated tissue MC exhibiting a round central nucleus; (ii) atypical MC type I with oval nuclei, hypogranulated cytoplasm, and prominent surface projections; (iii) immature atypical MC with bi- or polylobed nuclei (atypical MC type II = promastocytes); and (iv) metachromatic blasts. Type I atypical MC were detected in a patient with indolent SM, whereas type II MC and metachromatic blasts were primarily found in MML, MCL and tryptase-positive AML. In all samples examined, the identity of MC could be reconfirmed by immunoelectron microscopy, irrespective of the stage of cell maturation or the disease variant, all types of MC contained tryptase in their cytoplasmic granules.


CONCLUSIONS
Immunoelectron microscopy may be a helpful approach in confirming the identity of neoplastic MC in myeloid neoplasms.
Samorapoompichit
P
P
Centre of Anatomy and Cell Biology, Institute of Histology & Embryology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
Schernthaner
G-H
GH
Worda
C
C
Wimazal
F
F
Krauth
M-T
MT
Sperr
W R
WR
Valent
P
P
D000328:Adult; D000368:Aged; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000201:enzymology / Q000648:ultrastructure; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D007946:Leukemia, Mast-Cell / Q000201:enzymology / Q000473:pathology; D007951:Leukemia, Myeloid / Q000201:enzymology / Q000473:pathology*; D015479:Leukemia, Myelomonocytic, Acute / Q000201:enzymology / Q000473:pathology*; D008297:Male; D008407:Mast Cells / Q000201:enzymology* / Q000473:pathology / Q000648:ultrastructure*; D034721:Mastocytosis, Systemic / Q000201:enzymology / Q000473:pathology*; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D012697:Serine Endopeptidases / Q000032:analysis*; D053802:Tryptases
D012697:Serine Endopeptidases; D053802:Tryptases