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[224] Mammaglobin, a Novel Diagnostic Marker for Metastatic Breast Carcinoma

Z Wang, B Spaulding, G Nielsen, A Sienko, Y Liang, H Li, J Ro, J Zhai. Weill College of Medicine Cornell University, The Methodist Hospital, Houston, TX; Dako North America Inc, Carpenteria, CA; Kingmed Center, Guangzhou, Guangdong, China

Background: Breast carcinoma is known for its wide morphologic spectrum and unpredictable clinical behavior. In case of a metastatic carcinoma, with the right demographic information, breast should be considered as one of the major primaries. The current ancillary tests, however, are suboptimal in terms of sensitivity and specificity. We evaluated the diagnostic utility of mammaglobin, a member of secretoglobin family, in distiguishing breast versus non-breast carcinoma.
Design: A total of 314 formalin-fixed paraffin-embedded tissue sections were immunostained using a mouse monoclonal antibody raised against human mammglobin (clone 304-1A5; Dako, Carpinteria, CA; 1:100). These sections consisted of 41 breast primary invasive ductal carcinoma paired with 41 metastases to ipsilateral axillary lymph nodes; 160 non-breast carcinomas (59 endometrium; 35 colon; 26 lung; 15 prostate; 6 kidney; 2 stomach; 4 liver; 4 ovary; 4 pancreas; 2 thyroid; 3 undifferentiated); 36 other tumors (4 astrocytoma; 4 carcinoid tumor; 4 Ewings sarcoma; 4 Hodgkin lymphoma; 4 leiomyoma; 4 MFH; 4 melanoma; 4 mesothelioma; 4 rhabdosarcoma); and 36 specimens of normal human tissue. Immunostaining intensity was graded as 1+ (weak), 2+ (moderate) and 3+ (strong); the staining proportion was recorded as percentage of tumor area. Staining with 2+ or above and10% or more was defined as being positive.
Results: A total of 31 of 41 (76%) primary breast carcinoma were positive for mammaglobin with cytoplasmic staining pattern. Lymph node metastases paralleled with their primaries both in signal intensity and extent. The staining profile and histological grade was not correlated, however, because the majority (85%) of this cohort was moderate to high grade carcinoma. In comparison, 6 of 59 (10%) endometrial carcinoma were positive for mammaglobin; tumors of other organs and normal tissues were uniformly negative.
Conclusions: The high sensitivity and specificity highlight the value of mammaglobin as a novel diagnostic marker for metastatic breast carcinoma. An endometrial origin should be considered as the major differential diagnosis for the mammaglobin positive metastatic carcinoma, which requires a careful clinicopathologic correlation.
Category: Breast

Wednesday, March 28, 2007

Poster # 50, Wednesday Afternoon