case_images: PMC7728126_01
case_images: Breast tissue infiltration by neoplastic lymphoid population (A, asterisk: mammary duct), consisting of small to medium-sized cells (B), some of which present plasmacytoid features (B), immunoreactive to PAX5 (C), CD5 (D), CD23 (E) and kappa light chains (F) antibodies. HE staining: (A) x20; (B) x400. Immunohistochemistry: (C-E) x100; (F) x40. PAX5: Paired box protein 5; CD: Cluster of differentiation; HE: Hematoxylin-Eosin
case_images: RJME-61-1-241-fig1.jpg
case_images: PMC7728126_01_RJME-61-1-241-fig1.jpg
case_images: F1
case_images: Histological examination revealed breast tissue infiltration by large nodular foci of lymphoid cells (Figure 1A). In addition, large aggregates of cells having plasmacytoid features were found (Figure 1B). Immunohistochemical analysis revealed positivity of the neoplastic lymphoid cells for CD20, PAX5 (Figure 1C), Bcl-2, CD5 (Figure 1D), CD23 (Figure 1E), CD43, whereas immunostainings for CD3, CD10, cyclin D1, Bcl-6 and CD138 were negative. The plasmacytoid cells showed monotypic kappa light (Figure 1F) and IgG heavy chain expression.