Fig. 1: Morphological and main immunohistochemical features of triple-negative invasive breast lobular carcinoma (TN-ILC) compared to control tumors.

Mild power view of pleomorphic TN-ILC (A) compared to classic hormone receptor-positive invasive lobular carcinoma (HR + ILC) (B) and triple-negative invasive ductal carcinoma (TN-IDC) (C) (H&E-saffron) with partial membranous immunostaining for cytokeratin 5/6 in TN-ILC (D) compared to negativity in HR + ILC (E) and diffuse and strong expression in TN-IDC (F). Diffuse nuclear positivity for androgen receptor in TN-ILC (G) and HR + ILC (H) compared to negativity in TN-IDC (I).