Image Description
A focus of tubular/ductular growth pattern in a secretory carcinoma of breast. The lumens contain abundant dense eosinophilic secretions that are PAS+ve and diastase-resistant. The nuclei are vesicular and uniform, round to oval with prominent nucleoli. Mitotic figures are rare.
Differential diagnosis includes - acinic cell carcinoma, invasive ductal carcinoma with microcystic or microglandular features, microglandular adenosis, and sometimes sclerosing adenosis.
About the Disease
Secretory carcinoma of the breast is a rare tumor that was initially described in children but the majority of cases have been reported in adults. It displays microcystic, solid, tubular/glandular, and pseudopapillary growth patterns. The tumor cells have abundant pale eosinophilic or amphophilic granular or vacuolated cytoplasm. The glandular/microcystic spaces contain PAS+ve diastase-resistant eosinophilic secretions. It is positive for alpha-lactalbumin, mammaglobin, lysozyme, S-100 protein and cytokeratins CK5/6 and CK8/18 with variable expression of CEA and GCDFP-15. They are usually negative for ER, PR, and HER2 and have a low Ki-67 labeling index. Secretory carcinoma of breast may be related to acinic cell carcinoma of salivary glands. A similar molecular genetic abnormality has been found in both tumors - a recurrent balanced chromosomal translocation, t(12;15)(p13;q25), which leads to the formation of ETV6-NTRK3 fusion gene. It is a relatively indolent tumor with an excellent overall prognosis.