Indian Journal of Urology
: 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

Correspondence Address:
Joseph Thomas
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
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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. [1] It was in 1910 that a nerve sheath tumor was first adequately described histologically by Verocay who labeled it a neurinoma. [2] The term neurilemmoma was in­troduced by Stout in 1953. [3] Herein we present a case of retroperitoneal neurilemmoma.

 Case Report

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. [1] 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. [1] 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.­ [2]

The treatment options of retroperitoneal neurilemmo­mas depends on whether it is benign or malignant type. In benign neoplasm simple enucleation is sufficient. [1] 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. [4]


1Miller PL, Tessler A, Alexander S. Pinck BD. Retroperitoneal Neurilemmoma. Urology 1978; 11: 619-623.
2Kim SH, Choi BI, Han MC, Kim Y II. Retroperitoneal Neurilemoma : CT and MR findings. AJR 1992; 159: 1023-1026.
3Robert HW, Rengachary SS. Neoplasam of peripheral nerves. In Neurosurgery (2 nd ed.): 3219-3220.
4Fletcher CDM. Diagnostic Histopathology of tumour (2"' edn.): Vol II. Chapter 27.