Breast Carcinoma

The gross specimen of the breast shown above, demonstrating a large, irregular mass with nipple retraction, is most consistent with which of the following diagnoses?

A 52-year-old postmenopausal woman from Delhi presents with a 3-month history of a painless, hard lump in the upper outer quadrant of her right breast. On examination, the mass is 2 cm, fixed to the chest wall, with overlying skin dimpling and a positive Peau d'orange appearance. Axillary lymph nodes are palpable and hard. Mammography shows a stellate lesion with microcalcifications. Core needle biopsy reveals invasive ductal carcinoma with intermediate nuclear grade. Immunohistochemistry shows ER+, PR+, HER2−. What is the most appropriate next step in management?

A 58-year-old woman from Mumbai presents with a 6-month history of spontaneous bloody nipple discharge from the left breast. Physical examination reveals a palpable mass beneath the areola. Mammography and ultrasound show a 1.2 cm mass in the subareolar region with dilated ducts. Ductography reveals a filling defect in the major duct. Excisional biopsy of the mass and involved duct is performed. Histopathology shows a papillary lesion with a fibrovascular core lined by epithelial cells without atypia, and intact myoepithelial layer. What is the diagnosis?

A 52-year-old postmenopausal woman presents with a palpable breast mass in the upper outer quadrant. Histopathology confirms invasive carcinoma. Which is the most common histological type of breast carcinoma?

Which histopathological feature best distinguishes invasive lobular carcinoma (ILC) from invasive ductal carcinoma (IDC) of the breast?