Xulei Sui,1 Peipei Feng,1 Xiaoyuan Sun,1 Peng Liang,1 Ying Liu,2 Guowei Zhang3 

1Department of Radiology, Yantaishan Hospital, Yantai City, 264001, People’s Republic of China; 2Department of Pathology, Yantaishan Hospital (East Courtyard), Yantai City, 264003, People’s Republic of China; 3Department of Radiology, Yantaishan Hospital (East Courtyard), Yantai City, 264003, People’s Republic of China

Correspondence: Guowei Zhang, Department of Radiology, Yantaishan Hospital (East Courtyard), No. 10087 Keji Avenue, Laishan District, Yantai City, 264003, People’s Republic of China, Tel +86-0535-6602048, Email zhangguoweiyt@163.com

Purpose: This study determined the digital mammography and ultrasonography imaging features of pure invasive micropapillary carcinoma of the breast (PIMPC) and the correlation with pathologic features.
Patients Methods: Nineteen patients diagnosed with PIMPC at Yantaishan Hospital from October 2015 to February 2022 were included in the study group. Forty patients with breast masses diagnosed as nonspecific invasive ductal carcinoma of the breast (NIDC) from July to December 2021 were included in the control group. Digital mammography and ultrasonography features were compared between the two groups.
Results: Patients with PIMPC had a younger age profile compared to patients with NIDC (P=0.017). Moreover, PIMPC masses were smaller than NIDC masses (P=0.040). Imaging features analysis revealed significant differences in age groups (< 45 years: χ²=5.971, P=0.044) and the presence of spiculations or the crab claw sign (χ²=8.583, P=0.004) between patients with PIMPC and NIDC. However, there were no statistically significant differences in the presence of calcifications, blood flow grading, pathologic molecular subtypes between the study and control groups. The Ki-67 proliferative index (χ²=1.052, P=0.389), vascular invasion (χ²=2.263, P=0.197), and lymph node metastasis (χ²=1.968, P=0.386) showed no significant differences between PIMPC and NIDC patients.
Conclusion: PIMPC imaging features show specificity, such as tiny breast masses, spiculated edges, or crab claw-like patterns, and malignant signs appeared when the lesion was < 2 cm in diameter. PIMPC mainly occurs in middle-aged women 45– 59 y of age. Patients with PIMPC and NIDC of the breast are frequently associated with lymph node metastases and greater than one-half of the cases (74%) were shown to have a Ki-67 index > 30%, suggesting a significant risk of recurrence and metastasis. Early therapeutic care for these patients is crucial. These results warrant further validation with additional samples from several centers due to the limited single-center sample size in the current study.

Keywords: pure invasive micropapillary breast carcinoma, digital mammography, ultrasonography, breast cancer, pathologic features