A rare pelvic mass in an adult woman: case report of a mature sacrococcygeal teratoma

Sacrococcygeal teratomas (SCTs) are rare germ cell tumors that predominantly occur in neonates and infants, with adult presentations being exceptionally uncommon. These tumors arise from pluripotent embryonic germ cells located in the coccygeal region and may contain a mixture of cystic, solid, fatty, and calcified components. Malignant transformation, although rare, is associated with increased tumor vascularity and aggressive behavior. We present the case of a 30-year-old woman with no prior medical history who presented with urinary incontinence. Initial ultrasound revealed a non-specific cystic pelvic mass, prompting further evaluation with pelvic magnetic resonance imaging (MRI). MRI demonstrated a well-circumscribed presacral mass with typical features of SCT, including cystic components and fatty areas showing signal suppression on fat-saturated sequences, with no evidence of invasion or malignancy. The patient underwent surgical excision, which remains the treatment of choice, and histopathology confirmed a benign mature teratoma. This case highlights the importance of including sacrococcygeal teratoma in the differential diagnosis of adult pelvic masses and reinforces the essential role of MRI in lesion characterization and preoperative planning.