Endometrial stromal sarcomas are low-grade malignant
tumors that may pose a diagnostic challenge, especially when they are present in an extrauterine site. Owing to the presence of an arborizing vasculature and cells with an undifferentiated appearance,
endometrial stromal sarcomas can be confused with several
soft-tissue neoplasms. We studied 17
endometrial stromal sarcomas, eight
hemangiopericytomas, 14
solitary fibrous tumors, and 16
synovial sarcomas immunohistochemically, detecting the following
antigens: CD10,
estrogen receptor,
progesterone receptor, bcl-2, CD34, smooth muscle
antigen, epithelial membrane antigen and
cytokeratin (AE1/AE3). Most
endometrial stromal sarcomas stained positively for CD10 (16/17),
estrogen receptor (17/17),
progesterone receptor (15/17), and bcl-2 (17/17). Staining with antismooth muscle
antigen was seen in 11 of 17 cases of
endometrial stromal sarcoma, with more intense staining seen in areas showing smooth muscle differentiation. Staining with AE1/3 was seen in four of 17
endometrial stromal sarcomas, with two of the positive cases containing epithelioid cells. None of the
endometrial stromal sarcomas expressed
epithelial membrane antigen or CD34. More than half of the
hemangiopericytomas (4/8) and
solitary fibrous tumors (9/14) cases demonstrated CD10 expression either focally or in a patchy cytoplasmic and membranous pattern.
Hemangiopericytomas,
solitary fibrous tumors, and
synovial sarcomas did not express
estrogen receptor. Four of eight
hemangiopericytomas and seven of 14
solitary fibrous tumors also showed patchy
progesterone receptor expression. CD34 expression was identified in six of eight
hemangiopericytomas and 13 of 14
solitary fibrous tumors, but we did not find expression of CD34 in
synovial sarcoma. Differences between
endometrial stromal sarcoma and other soft-tissue
tumors were detected for all of the immunohistochemical markers (P<0.05), except anti-bcl-2 and AE1/3.
Antibodies against CD10 mark a substantial number of
hemangiopericytomas and
solitary fibrous tumors (albeit not diffusely) and should always be combined with
antiestrogen receptor and CD34 when the differential diagnosis includes
endometrial stromal sarcoma. Unlike
estrogen receptor antibodies,
progesterone receptor antibodies show at least focal nuclear staining in most
hemangiopericytomas,
solitary fibrous tumors and rare
synovial sarcomas, and are not useful for this differential diagnosis. All
endometrial stromal sarcomas expressed bcl-2, mostly in a diffuse pattern, but this did not distinguish between
endometrial stromal sarcoma and mimics. We therefore recommend the use of a small antibody panel comprising anti-CD10, anti-
estrogen receptor, and anti-CD34 to distinguish
endometrial stromal sarcomas from
tumors with a predominant hemangiopericytomatous growth pattern.