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    ABSTRACT: Differentiating between dermatofibrosarcoma protuberans (DFSP) and hypercellular dermatofibroma (DF) can sometimes be challenging, and a panel of immunostains is often employed. Expression of conventional markers oftentimes overlaps. We evaluated CD99 expression in DFSP and DF and its utility in distinction between these 2 entities. CD99 immunostaining was performed on 34 DFSPs and 24 hypercellular DFs. The intensity of staining was graded as "weak," "moderate," or "strong," and the proportion of positive cells was graded as follows: "scattered" when individual cells comprised <5% of the total cellularity of the lesion; "focal" with >5% but <25% of the cells; or "diffusely distributed" with staining of >25% of lesional spindle cells. Overall, DFSPs showed positive CD99 staining in 21 (61.76%) cases. Moderate and weak patterns of staining were the most frequent, seen in 13 (38.2%) and 7 (20.6%) cases, respectively. CD99 staining in DFSPs was predominantly scattered or patchy (4 and 11 lesions respectively) with less than 25% of cells expressing CD99. In comparison, all 24 DF cases showed strong CD99 positivity in >25% of the spindle cell component (P = 0.0003). The most striking difference related to the distribution of staining. In DFSP, tumor cells in the superficial dermis, when present, were always CD99 negative. In contrast, DF cells in the superficial dermis always demonstrated strong CD99 positivity. DF strongly expresses CD99 in a diffuse pattern that may serve as evidence in distinction from DFSP. As the differences in staining were most pronounced in the superficial portions of the tumor, CD99 staining may be well suited to superficial biopsy specimens, where distinction in hematoxylin and eosin sections may be most problematic.
    The American Journal of dermatopathology 11/2013; · 1.30 Impact Factor
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    Revista Cubana de Hematología, Inmunología y Hemoterapia. 04/2001; 17(1).
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    ABSTRACT: The expression of c-kit receptor (c-kit R; CD117) and CD34 was examined in acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), chronic myeloid leukemia (CML) in blastic transformation (BT), and myelofibrosis (MF) in myeloid BT. In myeloid leukemia including AML, CML-myeloid BT and MF-myeloid BT, both c-kit R and CD34 were expressed synchronously, while in lymphoid leukemia including ALL and CML-lymphoid BT, only CD34 was highly expressed. A close correlation between c-kit R and CD33 expression and an inverse correlation between c-kit R and CD 19 expression were observed when all of the myeloid plus lymphoid leukemia cells were analysed. There was a close correlation between c-kit R and CD34 expression in the myeloid leukemia cells, c-kit R expression may be associated with myeloid phenotypes of leukemic cells and may be useful for the diagnosis of myeloid leukemia. The literature of c-kit R expression in leukemic cells is reviewed here and the comparison of c-kit R and CD34 expression in normal hematopoietic progenitor cells with those on the leukemic counterparts was discussed.
    Leukemia & Lymphoma. 07/2009; 16(3-4).