Exploring MRI and Mammography Lesion Features for Breast Cancer Detection in PTEN Hamartoma Tumor Syndrome

(1) Background/Objectives: Women with PTEN hamartoma tumor syndrome (PHTS) face a significantly increased risk of breast cancer (up to 66%) and a high prevalence of benign breast lesions (30-75%), which can complicate cancer detection and underscore the need for effective surveillance strategies. This study aimed to evaluate the imaging characteristics of breast cancers and benign breast lesions using magnetic resonance imaging (MRI) and mammography, with the goal of improving early cancer detection, reducing unnecessary biopsies, and guiding future surveillance protocols. (2) Methods: This retrospective single-institution study included 65 PHTS women aged ≥18 years (2001-2021), 39 of whom participated in a high-risk breast cancer surveillance program. Imaging features of breast cancers from MRI and mammography (when available) and of benign breast lesions from MRI only were assessed independently by two breast radiologists and correlated with pathology reports. Sensitivity and performance of MRI and mammography in detecting breast cancers and benign breast lesions were analyzed using descriptive statistics and correlation analyses, with significance set at p < 0.05. (3) Results: Imaging was available for re-evaluation for 17 breast cancers (with MRI available for 10 cases and mammography for 15 cases) diagnosed in 11 women and 31 benign breast lesions (with MRI available for 29 cases and mammography for 26 cases) in 16 women. MRI identified 90% (9/10) of the breast cancers for which it was available as suspicious, with malignant features retrospectively identifiable in 50% of baseline scans. In comparison, mammography identified only 40% (6/15) of breast cancers and was notably less effective in women with dense breast tissue. For benign breast lesions, MRI identified all lesions (29/29), while mammography underperformed, correctly identifying only 58% (15/26). However, ambiguous enhancement features on MRI occasionally posed challenges in distinguishing between benign breast lesions and malignancies. (4) Conclusions: MRI significantly outperformed mammography in accurately characterizing both breast cancers and benign breast lesions in women with PHTS, particularly in younger women with dense breast tissue. These findings reinforce the critical role of MRI as the primary surveillance tool for this high-risk population, given that breast cancers in women with PHTS tend to exhibit typical malignant features on MRI. However, they also highlight the importance of careful interpretation of MRI findings for benign breast lesions and the need for additional strategies to minimize unnecessary interventions.