CD10 has been demonstrated to be positive in
endometrial stromal sarcoma (ESS) and thus is useful in establishing the diagnosis, but its expression in malignant müllerian mixed
tumor (MMMT) and müllerian
adenosarcoma remains to be clarified. In this study, 12 cases of MMMT (9 uterine, 2 tubal, and 1 metastatic), 6 cases of müllerian
adenosarcoma (three corporeal, two cervical, and one tubal), and 7 cases of primary uterine
sarcomas had their tissues examined immunohistochemically for expression of CD10,
desmin,
myoglobin, alpha-smooth muscle actin (SMA), and
cytokeratin. Of the primary uterine
sarcomas, two were primary
rhabdomyosarcomas (one cervical and one corporeal), two were ESSs, two were high-grade
leiomyosarcomas, and one was a high-grade endometrial
sarcoma. Sarcomatous components in all cases of MMMT and müllerian
adenosarcoma, as well as all uterine
sarcomas, were positive for CD10, showing moderate to marked staining intensity with varying distribution except in one MMMT, which showed weak and very focal staining. In four MMMTs, three
adenosarcomas, and one
rhabdomyosarcoma,
myoglobin- and/or
desmin-positive rhabdomyoblastic cells were positive for CD10. The immunoreactivity for CD10 showed the same distribution for alpha-SMA and
myoglobin in three and two MMMTs, respectively. In five cases of MMMT, carcinomatous components were focally positive for CD10, and in two cases small populations of round or short spindle cells in sarcomatous components were positive for CD10, alpha-SMA, and
cytokeratin (
CAM5.2). These results indicate that CD10 expression is not restricted to ESS but can be positive in MMMT and müllerian
adenosarcoma as well as in a variety of uterine
tumors including high-grade
leiomyosarcoma and
rhabdomyosarcoma. CD10 expression might be one of the characteristics of müllerian system-derived neoplastic mesenchymal cells.