The illusion of malignancy: a rare case of post-hysterectomy gossypiboma misinterpreted as ovarian cancer.

Introduction and importance: Gossypiboma, or retained surgical sponge, is a rare iatrogenic complication post-surgery, often mimicking malignancies like ovarian cancer in postmenopausal women. This leads to unnecessary oncologic interventions, patient anxiety, and procedural risks. Incidence ranges from 1:1000 to 1:18 000 procedures, with hysterectomies at higher risk due to human errors in counting. Recognizing imaging features is crucial to prevent misdiagnosis, highlighting the importance of multidisciplinary evaluation and preventive protocols in gynecological surgery. Case presentation: A 56-year-old asymptomatic postmenopausal woman, 9 years post-hysterectomy for fibroids, underwent routine transabdominal ultrasound revealing a 7.23 × 15.63 × 16.30 cm heterogeneous right adnexal mass initially interpreted as malignant ovarian neoplasm by a junior radiologist. Senior review and CT scan showed whorled structure with sterile gas, suggesting gossypiboma. Clinical discussion: Gossypibomas can remain latent for years, presenting as fibrotic masses with gas on imaging, mimicking tumors. Diagnostic pitfalls arise from inexperience, as seen here, but pathognomonic signs like spoke wheel patterns aid differentiation. Complications include obstruction or fistula; management involves surgical removal. Prevention requires standardized counting, radiopaque markers, and education to eliminate never events. Conclusion: This case emphasizes the need for high suspicion of gossypiboma in post-hysterectomy adnexal masses to avoid erroneous cancer diagnoses. Adhering to safety protocols enhances surgical integrity and patient outcomes.