1/4. Mast cell sarcoma with tissue eosinophilia arising in the ascending colon.Mast cell sarcoma is a rare disease. We report an unusual case of this neoplasm arising in the ascending colon of a 32-year-old Japanese woman who presented with abdominal pain. An ulcerating mass in the colon was resected, along with enlarged mesenteric lymph nodes. Two years after surgery, the neoplasm recurred as left cervical lymphadenopathy and an intra-abdominal mass. Despite predonine and radiation therapy, the disease progressed, and the patient died. The tumor cells had abundant fine granular or clear cytoplasm, and oval, lobulated, or indented nuclei. Numerous mature eosinophils were intermingled with the tumor cells. Immunohistologic studies on paraffin sections demonstrated that the majority of the tumor cells were strongly positive for CD45RB, CD68, and mast cell tryptase. They were unreactive, however, with a broad spectrum of antibodies against myelomonocytic and lymphocytic antigens. The mast cell nature of this rare type of tumor can be best identifiable by immunostains for mast cell tryptase.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/4. Morphologic and immunophenotypic properties of neoplastic cells in a case of mast cell sarcoma.Mast cell sarcoma is an extremely rare and aggressive type of mast cell disease. Only a few cases have been described so far, and little is known about the biology and phenotype of afflicted cells. We describe morphologic and immunophenotypic properties of neoplastic mast cells in a case of an intracranial mast cell sarcoma. In Wright-Giemsa-stained cytospin preparations, the morphology of dispersed cells appeared to be highly atypical with a considerable percentage of metachromatic blasts and mast cells with bilobed or multilobed nuclei. Combined toluidine blue/immunofluorescence staining revealed expression of CD13, CD45, CD88, CD116, and CD117 (c-KIT) on neoplastic mast cells. As assessed by immunohistochemistry, mast cells were immunoreactive for tryptase and CD68R, In contrast, the CD2 antigen that is expressed in mast cells in patients with indolent systemic mastocytosis was not detectable. mast cells also failed to display the c-KIT mutation Asp-816-Val, which is typically found in systemic mast cell disorders. Together, neoplastic mast cells in a case of mast cell sarcoma were found to exhibit unique morphologic, phenotypical, and molecular features when compared with mast cells in indolent mastocytosis or normal tissue mast cells.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
3/4. A case of malignant mastocytosis with circulating mast cell precursors: biologic and phenotypic characterization of the malignant clone.The phenotypic and biologic properties of malignant cells in a case of aggressive mastocytosis with multi-organ involvement, circulating mast cell precursors and absence of skin infiltrates were analyzed. Circulating mast cell precursors were detected by immunostaining using antibodies against mast cell tryptase as well as by electron microscopy. These progenitors were tryptase /chymase- (MCT) and accounted for 10 to 20% of nucleated mononuclear blood cells (MNC). A subset of them contained metachromatic granules. As assessed by combined toluidine blue/immunofluorescence staining, the granulated mast cell precursors were found to express CD9 (P24), CD33 (gp67) and CD44 (Pgp-1), but not basophil-related markers (CD11b (C3biR), CDw17 (lactosylceramide), CD123 (il-3R alpha))or monocyte-related antigens (CD14, CD15). Expression of the mast cell growth factor (MGF) receptor, c-kit(CD117), was also demonstrable, whereas the skin mast cell marker C5aR (CD88) could not be detected on mast cell precursors. The ligand of c-kit, recombinant human (rh) stem cell factor (SCF = MGF), induced histamine release from circulating mast cell progenitors, whereas rhC5a, a potent skin mast cell-/basophil-agonist, was ineffective over the dose-range (10(-9) to 10(-7(M)) tested. Analysis of mast cell antigens in malignant mastocytosis or mast cell leukemias may be helpful to establish a diagnosis and to determine the phenotype of the clone.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
4/4. In vivo differentiation of mast cells from acute myeloid leukemia blasts carrying a novel activating ligand-independent C-kit mutation.The primary role of protooncogene c-kit in mast cell differentiation is supported by the development of mast cells from CD34 /CD117 (c-kit) myeloid precursors. growth factor independence, neoplastic transformation and differentiation of mast cells were found in association with c-kit activating mutations in both murine and human mastocytoma and mast cell diseases. We have identified a novel c-kit mutation (D816Y) in peripheral blood mononuclear cells from a patient with AML (M2), massive presence of mast cells in bone marrow and rapid progression of the disease. The mutation, a G-->T transversion at nt 2467 of the c-kit gene resulting in Asp816-->Tyr substitution, corresponds to the D814Y and D817Y mutations identified and characterized in the murine P815 mastocytoma and the rat RBL-2H3 mast cell leukemia cell lines. The absence of SCF transcripts that we found by RTPCR in the patient's blasts indicates that, also in humans, this activating mutation leads to SCF independent growth. The expression of the mutant allele on Kit signaling may be further enhanced by trisomy of chromosome 4 (carrying the c-kit gene) in the patient's blasts. From these findings it is concluded that mast cells could be generated from a leukemic CD34/CD117-positive clone, that combines the antigenic expression of mast cell precursor to the growth and differentiation factor-independence which was derived by the c-kit D816Y mutation.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |