Unexplained Vaginal Bleeding in a Postmenopausal Woman Reveals Concurrent Invasive Ductal Carcinoma: A Case Report with Diagnostic Insights

Background Postmenopausal vaginal bleeding is a common clinical concern that mandates investigations to exclude endometrial malignancy. While breast cancer rarely presents with gynecological symptoms, metastasis to the uterus is a known, albeit uncommon, phenomenon. We present a case where the workup for vaginal bleeding incidentally revealed primary breast cancer. Case presentation A 55-year-old postmenopausal woman presented with a two-month history of unexplained vaginal bleeding. Pelvic ultrasound revealed endometrial thickening. During the comprehensive clinical evaluation, a firm, nontender mass was identified in the left breast. Subsequent mammography and biopsy confirmed Grade 3 invasive ductal carcinoma (IDC). The patient underwent total abdominal hysterectomy, which revealed a benign pathology (proliferative endometrium, adenomyosis, and leiomyoma), confirming that the bleeding was unrelated to the breast cancer. She was treated with a modified radical mastectomy and appropriate adjuvant therapy. Conclusions This case highlights a fortuitous diagnosis of breast cancer prompted by the investigation of an unrelated symptom. This underscores the critical importance of performing a thorough, multisystem clinical examination, even when a presenting symptom points toward a single organ system. A comprehensive approach can lead to the early detection of concurrent, clinically silent malignancies.