Clinicocytopathology of breast cancers with a ring-like appearance on ultrasonography and/or magnetic resonance imaging

On breast cancer imaging some cancers have an anechoic or high-echoic zone in the tumor on ultrasonography and ring-shaped enhancement on contrast-enhanced magnetic resonance imaging (MRI) with high intensity in the central area of the tumor on T2-weighted imaging, necessitating their differentiation from benign disease. Thus, nine breast cancers with a ring-like appearance on imaging were analyzed on cytopathology. Histologically the cancer cells of these lesions showing a ring-like appearance were located in the periphery of the tumor, with a central hypocellular zone. Five such lesions with a thick, doughnut-like appearance were identified as cancers with acellular zones (CAC), and four lesions with a thinner, rim-like appearance as matrix-producing carcinomas (MPC). The percentage ratio of the cancer-zone width to the tumor diameter was 26.4 ± 7.8 and 8.0 ± 3.2 (mean ± SD), respectively ( P = 0.003). Cytologically, highly atypical, naked-nucleus cells were observed in eight of the nine cancers. In two MPC and three CAC, cartilage matrix and amorphous material, respectively, were observed in the background. In summary, the present series of breast cancers having a ring appearance on imaging did not have uniform cytopathological features. They were classified as MPC or CAC, and cytology was useful in their diagnosis and differentiation in some cases.