Supplementary Material for: Early Detection of DCIS Through Surveillance in a Patient With Peutz-Jeghers Syndrome: A Case Report

Introduction: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disorder characterized by mucocutaneous pigmentation and gastrointestinal hamartomatous polyps. Women with PJS have a significantly increased risk of breast cancer, with surveillance recommended from an early age.
Case presentation: We report a case of ductal carcinoma in situ (DCIS) in a 36-year-old woman with genetically confirmed PJS (STK11 c.580G>A, p. Asp194Asn). Breast surveillance included semiannual ultrasound, as she initially declined mammography due to concerns about radiation exposure. During routine ultrasound, a small hypoechoic lesion was noted. The patient consented to MRI, which revealed a non-mass enhancement extending near the nipple. A biopsy confirmed DCIS. Mammography subsequently revealed extensive microcalcifications. Right total mastectomy and sentinel lymph node biopsy were performed, followed by tissue expander placement and delayed implant-based reconstruction. Pathology confirmed ER-positive, PgR-positive, HER2-negative DCIS. No adjuvant therapy was given. She remains disease-free at 2.5 years postoperatively.
Conclusion: This case demonstrates that structured breast surveillance in PJS can facilitate early detection of breast cancer. It underscores the clinical value of regular surveillance in hereditary cancer syndromes and supports the inclusion of breast screening as part of the comprehensive management of PJS.