Microlobulated Margins, Internal Punctate High Echoes, and Enhancing Internal Septation As Important Diagnostic Clues for Invasive Solid Papillary Carcinomas of the Breast: A Case Report

Invasive solid papillary carcinoma (ISPC) of the breast is a rare disorder and has few reported typical image characteristics to date. An 81-year-old woman was referred to our hospital for the detailed examination of a breast mass incidentally detected on computed tomography. Mammography showed a microlobulated mass, 1.6 cm in size. Ultrasound showed an oval mass with microlobulated margins, internal punctate high echoes, and slightly enhanced posterior echoes. Magnetic resonance imaging of the tumor showed low signals on T1-weighted images, weak high signals on fat-suppressed T2-weighted images, and early and retained enhancing internal septation on dynamic studies. After the pathological diagnosis of breast cancer, the patient underwent a partial mastectomy and a sentinel node biopsy. Postoperative pathological study showed that the tumor had cancer cells growing in a solid fashion around the fibrovascular stalks, stromal reaction in the central areas, and fat tissue invasion. Immunostaining of the tumor showed estrogen receptor, progesterone receptor, synaptophysin, CD56, and chromogranin positivity; human epidermal growth factor receptor type 2 and p63 negativities; and a Ki-67 labelling index of 5%, leading to the diagnosis of ISPC. Diagnostic physicians should note that ISPC may have microlobulated margins, internal punctate high echoes, slight posterior echo enhancement, slight high signals on fat-suppressed T2-weighted images, and enhancing internal septation.