CD34, CD117, and actin expression in phyllodes tumor of the breast.
BACKGROUND
This study investigated the immunophenotypic patterns of CD34, CD117 (a product of the c-kit proto-oncogene), and actin (HHF35) in benign and malignant phyllodes tumors (PTs). We correlated the expression of CD34, CD117, and actin with histopathological grade.


RESULTS
We analyzed 19 cases (7 benign and 12 malignant cases) of PTs using immunohistochemical analysis. Six of 7 benign PT stromal lesions stained positively for CD34, while only 3 of 12 cases of malignant PT were focally CD34 positive (P = 0.0106). Only 1 of the 7 benign PTs stromal lesions expressed CD117. Nine of the malignant PTs were composed CD117-positive fibroblasts. This result demonstrated that CD117 expression is associated with the malignant potential of PTs (P = 0. 0106). Actin (HHF-35) expression was found in 8 of 12 cases of malignant PTs (P = 0.027), but in only 1 of 7 cases of benign PTs. Actin expression was significantly (P = 0.04) correlated to frequent mitotic activity (>5 mitoses per 10 high-power fields). The immunophenotypic markers were not related to tumor size. Additionally, we sequenced part of the juxtamembrane region of the c-kit proto-oncogene and found point mutations in two malignant PTs.


CONCLUSIONS
Our results demonstrated that expression of CD34 was associated with benign PTs, while CD117 and actin were preferentially expressed in malignant PTs. Our results implied that these immunohistological markers might be used for the histopathological grading of PTs.
Chen
C M
CM
Department of Pathology, Armed Forces Taoyuan General Hospital, Taoyuan County.
Chen
C J
CJ
Chang
C L
CL
Shyu
J S
JS
Hsieh
H F
HF
Harn
H J
HJ
D000199:Actins / Q000032:analysis* / Q000235:genetics; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000032:analysis / Q000235:genetics; D018952:Antigens, CD34 / Q000032:analysis* / Q000235:genetics; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D008938:Mitosis; D008969:Molecular Sequence Data; D003557:Phyllodes Tumor / Q000235:genetics / Q000473:pathology*; D016133:Polymerase Chain Reaction; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis* / Q000235:genetics*
D000199:Actins; D015703:Antigens, CD; D018952:Antigens, CD34; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit