Cystic schwannoma of the pelvis

Abstract

Schwannomas are benign tumours that arise from the Schwann cells of nerve fibres. They commonly occur in the head and neck, mediastinum and extremities. They are extremely rare in the pelvis. These are usually slow-growing tumours and are often detected incidentally. Preoperative diagnosis is extremely difficult as there are no definitive signs on imaging. Aspiration biopsy is often inconclusive or misleading. Surgical excision is both diagnostic and therapeutic. As these tumours are often large in size, open excision is most commonly performed. We describe a case of a large, cystic schwannoma of the pelvis causing bladder outlet obstruction and bilateral hydroureteronephrosis. Complete surgical excision was performed laparoscopically.

Figure 1

Cystic schwannoma imaging: Ultrasonography of the urinary bladder showed the cystic space occupying lesion (SOL) with multiple septations (a). Computed tomography of the abdomen showed a well defined cystic SOL (11cm × 8cm × 7cm) with multiple areas of focal calcification in the wall. The bladder and the rectum were pushed to the right (b). Coronal sections demonstrated the SOL to be intricately related to the left psoas muscle (c). There was bilateral hydroureteronephrosis (d).

Figure 2

Cystic schwannoma: The mass as seen on laparoscopy (arrow) with the left iliac vessels (dotted arrow) (a). The mass was dissected from the left iliac vessels (b). The gross specimen revealed multiple septations and focal areas of calcification in the wall (c). Microscopic examination (haematoxylin and eosin stain, 10× magnification) revealed the elongated, spindle shaped cells with prominent nuclei arranged in a palisading manner with Antoni A and Antoni B patterns suggestive of a schwannoma (d).