Retroperitoneal ancient schwannoma: multidetector CT findings

Description

A 24-year-old man presented to our clinic complaining of right iliac fossa pain. Abdominal examination showed a non-tender, firm mass with well-defined borders. The patient was not sure when the symptoms started. His urine analysis, routine haematological parameters and renal function tests were within normal limits.

A direct urinary system graphy revealed a large mass in the right abdomen (figure 1). Multidetector CT of the abdomen verified a round, well-defined mass measuring 11 cm in diameter (figure 2). The mass was in retroperiteneum, and originating from the right L1–2 intervertebral foramen (figure 3). The lesion was homogeneous. Peripheral contrast enhancement and internal calcifications were noted. Any prominent bone erosion could not be revealed.

Figure 1.

Anteroposterior radiograph of the urinary system shows soft tissue mass in the right abdomen. There is scoliosis of the lumbal vertebral column.

Figure 2.

Axial contrast-enhanced CTimage of the abdomen. A well-defined mass in the retroperiteneum expanding to the right 1–2 lumbar intervertebral foramina(arrows). Right paravertebral muscles cannot be distinguished. Caput of the pancreas displaced to the anterior (*).

Figure 3.

Coronal and sagittal multidetector CT images show the mass originates from right 1–2 lumbar intervertebral foramina.

The patient underwent surgical excision of the mass. Histopathological evaluation confirmed the diagnosis of schwannoma.

Schwannoma (neurilemmoma) is a peripheral nerve sheath tumour and commonly occurs on the head, neck and trunk. Giant schwannoma is rarely located in the retroperiteneum and pelvis.¹ These tumours slowly increase in size before becoming symptomatic. Clinical signs or symptoms manifest themselves only by the compression or infiltration of adjacent organs.² Therefore, detection is often accidental as similarly in our case.

Schwannoma typically appears as a solitary, well-capsulated, firm and smooth-surfaced round mass. In large tumours (8–10 cm), a degenerative pattern, that is, the ‘ancient’ variant(cystic areas, calcifications, interstitial fibrosis and hyalinisation), is commonly found.

Surgical resection is enough to treat the tumour. Schwannoma is usually a benign tumour and malignant transformation is very rare.

Learning points.

• Slow-growing tumours may not give symptoms until they reach a large size.

• Nerve sheath tumours should be listed in differential diagnosis of retroperitoneal masses. An extension of the mass to the neural foramen is a helpful factor in diagnosis.