A Case Report of Multiple Primary Malignancies Presenting With Unusual Inguinal Metastasis

Multiple primary cancers (MPC) refer to the occurrence of two or more distinct malignancies in a single individual, either synchronously or metachronously. With advances in diagnostics and surveillance, the detection of MPC is increasing, requiring personalized management strategies. We report the case of a 65-year-old female with a history of metachronous rectal (1993), ovarian (2014), and papillary thyroid cancer (2024). Following prior surgeries and systemic treatments, a subcutaneous ulcerated mass appeared in the left inguinal region. Imaging and biopsy confirmed papillary thyroid carcinoma metastasis. The mass was surgically excised, and complex dermofascial flap reconstruction was performed. Postoperative recovery was uneventful. Genetic analysis revealed a CHEK2 p.Thr519Met (c.1556C>T) variant of uncertain significance. This case highlights the complexity and aggressive behavior associated with MPC. The presence of three separate malignancies, along with an unusual inguinal metastasis and a potential genetic predisposition, underscores the importance of long-term follow-up and molecular evaluation. CHEK2 variants, though of uncertain clinical significance, may play a role in multi-tumor predisposition. Clinicians should maintain a high index of suspicion for MPC in cancer survivors presenting with new lesions. Early recognition and a multidisciplinary approach are vital for optimal outcomes. Further studies are needed to clarify the genetic basis and prognostic implications of MPC.