Radiopathologic Characteristics of Invasive Mammary Carcinoma With Medullary Features: A Correlative Study

TL;DR

This study examines the radiologic and histopathologic features of medullary breast cancer to improve diagnosis accuracy and avoid misinterpretation due to its benign-like imaging appearance.

Contribution

The study provides a detailed radiopathologic correlation of medullary breast cancer, highlighting its diagnostic challenges and the necessity for histopathological confirmation.

Findings

Medullary carcinoma often appears as irregular masses with circumscribed margins on mammograms and hypoechoic masses with microlobulated margins on ultrasound.

Imaging features like posterior acoustic enhancement are common but not definitive for diagnosis, necessitating histopathological confirmation.

Histopathology reveals a syncytial growth pattern, high nuclear grade, and absence of glandular elements in most cases.

Abstract

Introduction

Invasive mammary carcinoma with medullary features represents an uncommon subtype of breast cancer. Despite their high-grade histological appearances, they have a favourable prognosis. This study aims to correlate its radiologic and histopathologic characteristics. A comprehensive understanding of the radiopathologic profile is essential for enhancing the diagnosis precision and guiding patient treatment, particularly because of its typically benign imaging findings, which may result in misinterpretation and underdiagnosis.

Materials and methods

A retrospective observational study was conducted by reviewing cases of histologically confirmed invasive mammary carcinoma with medullary features and triple-negative basal-like carcinoma that met the WHO criteria over five years (2020-2025) at the Sri Ramachandra Institute of Higher Education and Research, Chennai, India. We reviewed preoperative mammographic and ultrasound features and compared them with histopathological findings. Descriptive statistics summarise the prevalence of each feature.

Results

We included a total of 45 patients (age range: 25-76 years) with a confirmed diagnosis of medullary carcinoma. On mammograms, 30 (90.9%) had a detectable mass, of which 16 (53.3%) presented as an irregular shape with circumscribed margins and equal density. Rarely were calcifications identified, and they were present only in three (10%) cases. Sonographic examination revealed 29 (83%) cases as hypoechoic; 26 (74%) irregular masses, with microlobulated margins in 18 (51.4%) cases; and posterior acoustic enhancement in 32 (91%) cases. Eighteen (51%) of the masses showed minimal internal vascularity. Histopathology confirmed that 42 (93%) of the cases showed a syncytial growth pattern, with 39 (86%) having a high nuclear grade and 44 (97.8%) showing no glandular or tubular elements. There were prominent lymphoplasmacytic infiltrates in 100% of cases, and they were all triple-negative immunophenotypes.

Conclusion

Medullary carcinoma can present similarly to benign lesions in imaging studies, exhibiting characteristics like circumscribed morphology and posterior acoustic enhancement. Despite these similarities, imaging techniques cannot definitively differentiate medullary carcinoma from other types of breast lesions, making it essential to conduct a biopsy and obtain histopathological confirmation for a conclusive, timely, and accurate diagnosis.

Figures