Complicated Tailgut Cyst with Infection and Vaginal Fistulization in a 49-Year-Old Woman: MRI Contribution and the Role of CT-Guided Biopsy and DrainageComplicated Tailgut Cyst with Infection and Vaginal Fistulization in a 49-Year-Old Woman: MRI Cont

Tailgut cyst, also known as retrorectal cystic hamartoma, is a rare congenital lesion arising from remnants of the post-anal gut and typically located in the retrorectal space [1, 2]. It predominantly affects adult women and may remain asymptomatic until complicated by infection, hemorrhage, fistulization, or, more rarely, malignant transformation [1, 3]. We report the case of a 49-year-old woman with no notable past medical history who presented with chronic proctologic symptoms. Digital rectal examination revealed extensive pararectal induration. Laboratory tests showed a white blood cell count of 10,000/mm3 and a C-reactive protein level of 9 mg/L, with no other remarkable abnormalities. Pelvic MRI demonstrated a multiloculated retro-anal cystic lesion extending into the retro-anal fat, showing heterogeneous signal intensity with fluid content, hemorrhagic foci hyperintense on T1-weighted imaging, and additional T2-hyperintense areas with diffusion restriction and peripheral enhancement, suggestive of abscessed changes with fistulization toward the vagina. CT-guided biopsy and drainage were performed using a 16G, 15 cm semi-automatic needle with a coaxial system. The patient was started on dual antibiotic therapy, and the first follow-up assessment was highly favorable. Additional surgical drainage was proposed. Histopathological results are pending. Overall, the clinicoradiologic presentation was primarily suggestive of a complicated tailgut cyst. This case highlights the key role of MRI in characterizing complicated retrorectal lesions and supports a multidisciplinary management strategy, while complete surgical excision remains the definitive treatment reported in the literature [1-4].