Year : 2002 | Volume
: 18 | Issue : 2 | Page : 187--188
Retroperitoneal cystic neurilemmoma
K Natarajan, Mahesh Rao, Padmaraj Hedge, Joseph Thomas, K Sasidharan, Manna Valiathan, Sudha S Bhat
Division of Urology and Department of Pathology, Kasturba Medical College, Manipal, India
Department of Urology, KMC, Manipal, Karnataka - 576 119
|How to cite this article:|
Natarajan K, Rao M, Hedge P, Thomas J, Sasidharan K, Valiathan M, Bhat SS. Retroperitoneal cystic neurilemmoma.Indian J Urol 2002;18:187-188
|How to cite this URL:|
Natarajan K, Rao M, Hedge P, Thomas J, Sasidharan K, Valiathan M, Bhat SS. Retroperitoneal cystic neurilemmoma. Indian J Urol [serial online] 2002 [cited 2021 Sep 28 ];18:187-188
Available from: https://www.indianjurol.com/text.asp?2002/18/2/187/37643
Neurilemmoma is a benign neurogenic tumor arising from the sheath of peripheral nerves in the soft tissues of the head and neck, extremities, mediastinum and retroperitoneum.  It was in 1910 that a nerve sheath tumor was first adequately described histologically by Verocay who labeled it a neurinoma.  The term neurilemmoma was introduced by Stout in 1953.  Herein we present a case of retroperitoneal neurilemmoma.
A 30-year-old male presented with fullness in the left lumbar region for one year, early satiety of 2-weeks' duration and loss of appetite. There were no other symptoms or systemic illnesses. Examination showed a large retroperitoneal firm mass with smooth surface in the left lumbar region extending on to the left iliac fossa.
Ultrasonogram revealed a cystic mass with mixed echogenicity measuring 12 x 10 cm below the left kidney. Evaluation with CT scan revealed a large unilocular. encapsulated, peripherally enhancing retroperitoneal cyst, inferiorly disposed to the left kidney and lying beneath the psoas muscle [Figure 1]. A possibility of psoas abscess and retroperitoneal hemorrhage was considered.
Percutaneous drainage was carried out which drained 300 ml hemorrhagic fluid initially and 100-150 ml for the next 5 days. Cytology of the hemorrhagic fluid was negative for malignant cells. In view of the hemorrhagic nature of the fluid and persisting drainage, exploration was carried out. On exploration a large, well encapsulated cystic retroperitoneal mass with solid elements was found beneath the psoas muscle which was tethered to the posterior abdominal wall by the lumbar nerve roots with no obvious intra-spinal extension. Excision of the cystic mass was carried after dividing the lumbar nerve roots.
Histopathological examination revealed highly ordered cellular component (Antoni type A tissue) and loose myxoid component (Antoni type B tissue) present which was consistent with neurilemmoma [Figure 2].
Neurilemmoma is also known as benign schwannoma, neurinoma and perineural fibroblastoma.  It is an encapsulated tumor. It occurs usually in young to middle-aged adults. The occasional appearance of this tumor in the retroperitoneum makes this neoplasm of interest to urologists.
The early symptoms of benign and malignant retroperitoneal neurilemmomas are varied and none of the symptoms that occur can be considered diagnostic. Palpation of mass in the abdomen or flank is the first sign of tumor.  The investigative modalities of choice are computed tomography and magnetic resonance imaging.
On computerized tomography neurilemommas appear as well demarcated masses homogeneous on unenhanced scans and heterogeneous with ring-shaped enhancement after contrast administration. The areas of heterogeneity on enhanced scans are due to cystic and hemorrhagic changes. Magnetic resonance imaging finding of neurilemommas has been described as masses of low signal intensity on T1 weighted images and high signal intensity on T2 weighted images because of long TI and loner T2 relaxation times. 
The treatment options of retroperitoneal neurilemmomas depends on whether it is benign or malignant type. In benign neoplasm simple enucleation is sufficient.  However if there is evidence of local extension a malignant neoplasm should be considered and adequate margin of contiguous normal-appearing tissue should be included in the excision.
Histologically neurilemommas consist of two components, known as Antoni A & B tissues, in variable proportions. Antoni A tissue is cellular and consists of monomorphic spindle-shaped Schwann cells with poorly defined eosinophilic cytoplasm. Antoni B areas are composed of Schwann cells but their cytoplasm is inconspicuous and nuclei appear suspended in a copious myxoid, often microcystic, matrix. 
|1||Miller PL, Tessler A, Alexander S. Pinck BD. Retroperitoneal Neurilemmoma. Urology 1978; 11: 619-623.|
|2||Kim SH, Choi BI, Han MC, Kim Y II. Retroperitoneal Neurilemoma : CT and MR findings. AJR 1992; 159: 1023-1026.|
|3||Robert HW, Rengachary SS. Neoplasam of peripheral nerves. In Neurosurgery (2 nd ed.): 3219-3220.|
|4||Fletcher CDM. Diagnostic Histopathology of tumour (2"' edn.): Vol II. Chapter 27.|