case_images: PMC6594316_01
case_images: Histopathological analysis of perianal nodule biopsy. (a) Hematoxylin and Eosin (H&E) stain (original magnification 100x) showing anastomosing cords of basaloid cells with overlying connection to epidermis and stromal retraction. (b) Immunohistochemical staining for smooth muscle actin (original magnification 100x) showing diffuse, strong positivity. (c) Immunohistochemical staining for Ber-EP4 (original magnification 100x) showing diffuse, strong, membranous positivity.
case_images: CRIDM2019-6268354.001.jpg
case_images: PMC6594316_01_CRIDM2019-6268354.001.jpg
case_images: fig1
case_images: Microscopic exam confirmed the diagnosis of perianal BCC, nodular type (Figure 1(a)). Histopathology revealed a lesion strongly and diffusely positive for immunohistochemical staining of smooth muscle actin (SMA) (Figure 1(b)) and negative for carcinoembryonic antigen (CEA) and pancytokeratin (AE1/AE3), supporting the diagnosis. Staining for epithelial membrane antigen (EMA) was negative in the tumor cells while monoclonal antibody BER-Ep4 displayed strong and diffuse positivity, further supporting the diagnosis (Figure 1(c)).