[170] D2-40 Reactivity in Spindle Cell Lesions of the Breast

MT Galgano, KA Atkins, MR Wick, SE Mills. University of Virginia Health System, Charlottesville, VA

Background: The D2-40 antibody to podoplanin is a marker first described in lymphatic endothelium which has been noted in many malignant tumors including angiosarcomas and mesotheliomas, as well as normal tissues, including stromal cells of the breast. Given the potential considerations among spindle cell lesions of the breast and chest wall, characterization of D2-40 expression has diagnostic relevance.
Design: Our electronic database was searched for all primary breast lesions seen over a 12 year period that were described as metaplastic, spindle cell, sarcomatoid, or sarcomatous. Seven representative examples of low-grade phyllodes tumors were also included. Immunohistochemistry for D2-40 was performed and blindly scored for quantity (0, none; 1,<10%; 2,10-50%; 3, >50%) and quality (0,negative; 1, mild at 20x; 2, strong at 10x; 3, very strong at 2x). These values were multiplied and a resulting score of at least 6 was considered positive. Clinicopathologic data were collected on each case and reviewed, including IHC performed during routine clinical evaluation.
Results: 3 of the 7 metaplastic carcinomas were immunoreactive with D2-40. One of the positive cases plus one of the negative cases demonstrated partial reactivity for other vascular markers, and had been considered to represent pseudovascular carcinomas. Only 1 of 5 low-grade sarcomas, and none of the low-grade phyllodes tumors (n=7), or high-grade sarcomas without a history of local radiation (n=5) was positive. None of these was vasoformative or had documented reactivity for another vascular marker. All 5 high-grade sarcomas associated with past radiation for breast carcinoma were positive. Three of these had vasoformative areas plus reactivity for CD31. These features were lacking in the other two tumors, both of which demonstrated strong SMA staining.
Conclusions: Although spindle cell lesions of the breast are generally negative for D2-40, a subset of metaplastic carcinomas and radiation-induced sarcomas are positive, with or without supportive evidence of vascular differentiation.
Category: Breast

Monday, March 9, 2009 1:00 PM

Poster Session II # 53, Monday Afternoon