Author(s)

Nadège Gruel, Aurélie Cédenot, Marion Richardson, Paul Fréneaux, Jaydutt Bhalshankar, Thierry Dubois, Xavier Sastre-Garau, Olivier Delattre, Anne Vincent-Salomon

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INSERM Unit 830, Institut Curie, Paris, France.

Invasive micropapillary carcinomas (IMPC) of the breast account for less than 2% of all breast cancers and have been recently described as luminal B carcinomas. CD24, CD44, ALDH1 and EZH2 are commonly used as stem-cell markers that display differential expression as a function of stage and molecular type, but their pattern of expression according to this rare histological type remains poorly defined and unknown for EZH2. We assessed expression of these markers in a series of 28 micropapillary breast carcinomas and compared the results with those obtained in a series of luminal A (27 cases) and B (34 cases) invasive carcinomas not otherwise specified (IC-NST). CD24 and CD44 were expressed in most cases. However, CD24 was expressed at the inverted apical membrane in 85% of invasive micropapillary carcinoma and at the apical pole of gland-forming cells in 45% of luminal A (p-val = 6.8 × 10^－4) and 13% of luminal B cases (p-val = 1.1 × 10^－7). ALDH1 was expressed in the stroma in most tumors, but in only 25%, 11% and 15% in epithelial cells of IMPC, luminal A and B IC-NST, respectively. Nuclear expression of EZH2 was not observed in luminal A tumors, and was detected in 35% (12/34) of luminal B carcinomas (p-val = 6.1 × 10^－3) and only 4% (1/28) of invasive micropapillary carcinomas. This series shows that invasive micropapillary carcinomas harbor a CD24-positive inverted apical pole associated with weak EZH2 expression, phenotypical characteristics that distinguish this entity from other luminal carcinomas.

CD44; CD24; ALDH1; EZH2; Invasive Micropapillary Breast Carcinoma

N. Gruel, A. Cédenot, M. Richardson, P. Fréneaux, J. Bhalshankar, T. Dubois, X. Sastre-Garau, O. Delattre and A. Vincent-Salomon, "Inverted Apical CD24 and Weak EZH2 Expressions Are Phenotypic Characteristics of Pure Invasive Micropapillary Carcinoma of the Breast," Open Journal of Pathology, Vol. 3 No. 2, 2013, pp. 85-95. doi: 10.4236/ojpathology.2013.32016.