Interesting Breast Tumours: A Tripod of Cases

Knowledge regarding the lesser common breast tumours, including malignant papillary neoplasms and glycogen-rich clear cell carcinoma, is limited. Overall, cases of papillary carcinoma of the breast fare better than invasive breast carcinoma, from the data available in literature. Glycogen-rich clear cell carcinoma is characterized by the presence of clear cells, having mostly a poorer prognosis. We hereby present three such cases which would add to the existing available information. Case 1 is a 79-year-old female who presented with a left breast lump and bloody nipple discharge. Mammography suggested malignant lesion, with FNAC suspicious of malignancy. Surgery was done and histopathological examination showed irregular islands of tumour cells having papillary fronds with absence of myoepithelial layer. Immunohistochemically, the tumour was GATA3, CK7, ER, PR positive, HER2 negative, with Ki67 index 10%. The case was diagnosed as Solid papillary carcinoma. Case 2 is a 57-year-old female presenting with a left breast lump along with bloody nipple discharge. Mammography and FNAC were in favour of malignancy. Trucut biopsy was done, microscopy revealing a tumour having >90% papillary architecture with infiltrative pattern. Features were suggestive of Invasive breast carcinoma with papillaroid features. The tumour was GATA3, CK7, ER, PR positive, HER2 negative, with Ki67 index 15%. Case 3 is a 70-year-old female presenting with a right breast lump with nipple retraction. Mammography and FNAC were suggestive of malignancy. Trucut biopsy followed by microscopy revealed polygonal tumour cells with clear cytoplasm in nested pattern, showing positive staining for Periodic Acid Schiff. Immunostaining showed GATA3 positive, PAX8 negative, ER and PR positive, HER2 negative, and Ki67 index 20%. A diagnosis of Invasive breast carcinoma with Glycogen-rich clear cell pattern was made. Identifying these rare entities is important along with assessing hormone status for avoiding overtreatment and undertreatment and applying appropriate targeted therapies.