Interobserverer variability of lobular neoplasia

Abstract

734 Background: Lobular neoplasia(LN) is presumed to have a distinct biological and phenotypical tumor characteristics, and clinical implication different from ductal neoplasia(DN). The histological diagnoses of either DN or LN or both can be problematic in those tumors with low grade morphological features.The interpretation can vary among pathologists. E-cadherin has shown to be useful in distinguishing DN or LN on the basis of complete membrane stain. In this pilot study, the accuracy and variability of histomorphological interpretation of LN was studied by using E-cadherin expression as a gold standard. Methods: Forty seven cases of breast lesions previously diagnosed as LN during the period of 1998 to 2002 were randomly selected from the departmental files in a 400 bed community hospital. Four surgical pathologists reviewed the slides in a blinded manner for the histopathologic interpretation. E-cadherin stain was conducted on the paraffin-embedded sections of the breast lesions using E-cadherin antibodies (prediluted, Cell Marque, Hot Springs, AK) and DAKO automated immunostainer after antigen retrieval with appropriate positive and negative controls. Only complete E-cadherin membrane reactivity of epithelial cells was recorded as positive.Incomplete membrane stain was considered as aberrant and absent staining as negative. Benign breast ducts used as positive internal control. Results: The histologic diagnoses of LN was confirmed by E-Cadherin stain in 76.5%(36/47) of the cases: of these 36 cases, 27 were diagnosed as LN on routine H&E stain by two or three pathologists and 9 were by one pathologist. E-cadherin stain changed the diagnoses of LN to DN in 12.7%(6/47), DN to LN in 6.3%(3/47) and DN to mixed LN/DN in 4.2% (2/47). E-cadherin membrane immunoreacivity appears to be heterogenous and does not always show complete absent membrane staining. Conclusions: The study confirms variability in interpreting LN on routine H&E stain among pathologists, and E-cadherin stain is useful in classifying LN versus DN. As an accurate interpretation of LN is essential for the management of LN, the standardization of E-Cadherin antibodies and interpretation appears to be eminent No significant financial relationships to disclose.