Giant balloon-like presacral schwannoma

Abstract

A 69-year-old female patient visited a gynecologist because of lower abdominal discomfort. Magnetic resonance (MR) imaging was conducted, and the patient was referred to our institute because a presacral abnormal lesion was found. Physical examination revealed absence of neurologic compromise. Plain MR imaging revealed presacral single balloon-like cyst, which was homogenously low intensity on T1-weighted images and high intensity on T2-weighted images (Fig. 1A–C). The succeeding gadolinium-enhanced MR imaging revealed ring enhancement of the lesion (Fig. 1D, E). The initial differential diagnosis of the lesion includes schwannoma, abscess, chordoma, and perineural cyst. We, together with the gynecologists, conducted a laparoscopic excisional biopsy of the lesion. After the aspiration of liquid in the cyst, total extirpation of the lesion was successfully performed. Histologic examination revealed spindle-shaped cells arranged in short bundles with foci of nuclear palisading. Neither nuclear atypia nor mitotic figures were observed. These findings were consistent with benign schwannoma. At the time of the latest follow-up, 2 years after the surgery, the patient was free of symptoms without evidence of regrowth of the lesion (Fig. 2, Left and Right). Sacral schwannomas have a very rare etiology, comprising less than 1% to 5% of all spinal schwannomas, and only around 50 cases have been reported in the literature [1]. Schwannomas can develop degenerative changes with cystic formations; however, purely cystic change is by far a rare finding in the spinal schwannoma, and only few cases of giant sacral schwannoma with significant cystic component have been reported in the literature [2]. Even though the lesion presents significant cystic component, most of the lesions present heterogeneous multilobulated mass. To the best of our knowledge, the single-lobulated giant presacral schwannoma is an extremely rare condition. We advocate that uneven thickness of the cystic wall is one of the factors distinguishing tumors from other simple cystic lesions like perineural cyst.