PMC5907396_01
Mammography of the right breast showing spiculated, irregular mass lesion measuring 1,5 x 1,4 cm, located at upper-outer quadrant. A secondary retromammary lesion measuring 1,9 x 1 cm was also detected.
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fig1
Mammography indicated two lesions (Figure 1).
Invasive lobular carcinoma of the breast with extra cellular mucin shows the classic pattern of lobular carcinoma with single cell infiltration and discohesive pattern (top); groups of tumor cells are seen floating in a pool of extracellular mucin (bottom) (a: hematoxylin-eosin; original magnification x20). Extracellular mucin lakes with clusters of tumor cells (b: hematoxylin-eosin; original magnification x40). Areas of classic invasive lobular carcinoma showing typical single cell infiltration of the stroma and discohesive pattern (c: hematoxylin-eosin; original magnification x40).
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There was a primary irregular lesion measuring 1,5 x 1,4 cm, located at upper-outer quadrant of the right breast, BI-RADS category was assessed to be 5, there was a second retromammary lesion measuring 1,9 x 1 cm with a benign appearance of category BI-RADS 1, core needle biopsy was performed in the primary suspect lesion, the microscope examination showed the presence of small uniform tumor cells floating in lakes of extracellular mucin, some cells showed signet ring cell morphology (Figures 2(a) and 2(b)), and areas of classical lobular carcinoma were noted with single cell infiltration (Figure 2(c)).
Immunohistochemical stain showed absence of membranous E-cadherin staining in the classical invasive lobular carcinoma and in the cells surrounded by extracellular mucin (a: E-cadherin x20) with positive internal control (b: E-cadherin x40). The tumor cells were positive for ER (c: ER x20) and negative for PR and HER2 (images not shown).
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On immunohistochemistry examination, The E-cadherin was negative in both areas of the tumor with positive internal control (Figures 3(a) and 3(b)) and the lobular origin was confirmed; chromogranin A and synaptophysin were also negative. Prognostic and predictive marker studies showed the positivity for estrogen (Figure 3(c)).