Lobular carcinoma of the breast with extracellular mucin: New variant of mucin-producing carcinomas?

Department of Pathology and Laboratory Medicine, University of Florida, Jacksonville, Florida 32209, USA.
Pathology International (Impact Factor: 1.69). 07/2009; 59(6):405-9. DOI: 10.1111/j.1440-1827.2009.02385.x
Source: PubMed


The presence of mucin in infiltrating lobular carcinomas has been described as occurring exclusively in an intracytoplasmic location. To the best of the authors' knowledge, infiltrating lobular carcinoma displaying extracellular mucin has not been described in the literature. Herein is presented a case of lobular carcinoma with extracellular mucin in a 60-year-old female patient, who also had a contralateral ductal carcinoma of the cribriform type. Histologically the tumor had the classical appearance of infiltrating lobular carcinoma with signet ring cells and 'Indian file' infiltration of the stroma as well as pools of extracellular mucin. It is of great importance to appropriately classify breast carcinomas as ductal or lobular in origin due to the different treatment, prognosis, and clinical behavior of these lesions. The present finding opens the door for discussion of the current knowledge concerning histological variants of lobular carcinoma and should alert pathologists to the fact that the presence of extracellular mucin in an otherwise classical infiltrating lobular carcinoma does not preclude this diagnosis.

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Available from: Amir Mohammadi, Md, Jan 08, 2014
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    • "Herein, we present a case of lobular carcinoma with extracellular mucin and signet ring component. Up to the now, only 2 cases of mammary invasive lobular carcinoma with extracellular mucin have been described in the English written literature [7,8]. "
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    ABSTRACT: The differences between invasive lobular and ductal carcinomas affect the diagnostic and therapeutic management for patients with breast cancer. In most cases, this can be accomplished because of distinct histomorphologic features. However, occasionally, this task may become quite difficult, in particular when dealing with the variants of infiltrating lobular carcinoma. Lobular carcinoma has been considered a variant of mucin-secreting carcinoma with only intracytoplasmic mucin. The presence of extracellular mucin is a feature of ductal carcinoma. Herein is presented a case of lobular carcinoma with extracellular and intracellular mucin in a 43-year-old female patient, and confirmed by immunohistochemistry. Up to the present, infiltrating lobular carcinoma displaying extracellular mucin has not been described in the literature except two case. Virtual slides The virtual slide(s) for this article can be found here:
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    • "While the diversity of growth patterns is a major contributing factor to the reproducibility problem, the cytologic features of classical lobular carcinoma cells seem to have some value in recognizing the lobular phenotype. In our current case, the tumor growth pattern and cytomorphologic features are characteristic of a classical type ILC, even though the extracellular mucin secretion in ILCs has almost never been documented in the literature until a recent case report [18]. "
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    ABSTRACT: Invasive lobular carcinomas (ILC) of breast typically demonstrate intracytoplasmic mucin. We present a unique case of classical type ILC with abundant extracellular mucin and strong ERBB2 (HER2/neu) expression confirmed by immunohistochemistry and fluorescent in situ hybridization. Dual E-cadherin/p120 immunohistochemical stain demonstrated complete loss of membranous E-cadherin and the presence of diffuse cytoplasmic p120 staining, confirming the lobular phenotype. The tumor cells showed ductal-like cytoplasmic MUC1 staining, but were negative for MUC2 and other mucin gene markers. In addition, studies of tissue microarrays of 80 breast carcinomas with mucinous differentiation revealed 4 pure mucinous carcinomas showing significantly reduced E-cadherin staining without redistribution of p120 into cytoplasm. The findings suggest that the presence of extracellular mucin does not exclude a diagnosis of lobular carcinoma, and the morphologic and molecular characteristics of lobular and ductal carcinomas are more complex than previously appreciated.
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