Introduction

Primary tumors of the retroperitoneal region are quite rare. The retroperitoneal masses may be cystic or solid, benign or malignant. The majority of solid retroperitoneal tumours are malignant (80%)[1].The benign tumours include leiomyomas, extra adrenal chromaffinomas, mucinous custadenomas and haemangiopericytomas, while the malignant tumours are lymphomas, soft tissue sarcomata, congenital neuroblastoma and neoplasms arising from the urogenital ridge¹.We report a rare case of ancient retroperitoneal schwannoma in 50-year-old female involving lumbar region and its management by complete laparoscopic excision.

Case Report

A 50-year-old female presented with history ofpain and swelling left flank for 1 year.Examination revealed a firm, non-tender,ballotable,bimanually palpable swelling approximately 7x5 cm occupying left lumbarandiliac fossa.Ultrasonography showed a mixed echogenicspace occupying lesion11x 7 cm with septations and internal echos displacing the left kidney.CECT revealed a 12x7.5 cm multiseptated cystic mass with peripheral calcification and solid component in left pararenal space separate from the kidney (Figure 1).

Hydatid serology was negative. Patient was taken up for transperitoneal laparoscopic cyst excision. Histopathology revealed ancient schwanoma confirmed by positive staining for S-100 protein (Figure2).

Discussion

Retroperitoneal schwannomas comprise only 1–10% ofall retroperitoneal tumours. As such Schwannomas usually involve the cranial and peripheral nerves in head,neck and limbs. However, schwannomas may rarely occur in retroperitoneum, accounting for approximately 3% of all schwannomas [2,3]. Retroperitoneal schwannomas are benign in nature, but malignant transformation has also been reported [2]. Within the retroperitoneum the schwannomas usually involve the presacral space and adrenal gland [4]. Preoperative diagnosis is often not possible,the presence of cystic lesion with semisolid areas seen on cross sectionalimaging may suggest the diagnosis but are not definitive [2]. The definitive diagnosis is made only by histopathology and immunohistochemistry(S-100 protein, vimentin&neuron specific enolase staining is positive whereas staining for CD 117 and smooth muscle actin is negative) [5,6].

Two histologically distinct patterns of schwannomas have been described: antony type A having irregular streams of elongated spindle cells, andantony type Bhaving areas of hypocellularity with predominantly loose myxoid matrix [7]. Ancients chwannoma is a rare variant of schwannomasdescribed by Ackerman and Taylor and are characterised by degenerative changes like cystic necrosis, Perivascular hyalinizition, calcification, xanthomatous change and degenerative nuclei [8,9]. Surgical excision is treatment of choice as schwannomas are not sensitive to chemotherapy and radiotherapy [10]. Most reported cases of ancient retroperitoneal schwannomas have been managed by open surgery thoughfew casereportshave describedlaparoscopic management of retroperitoneal schwannomas (Kang CM et al) [11].

To our best knowledge this is a rare case ofan ancient schwannoma involving the lumbar region that has beenmanaged by complete laparoscopic excision.We conclude that retroperitoneal schwannomas although rare, must be kept in mind as a differential diagnosis for lumbar retroperitoneal tumors and complete laparoscopic excision is possible.

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