|Year : 2014 | Volume
| Issue : 2 | Page : 368-370
Retroperitoneal ancient schwannoma: Two cases and review of literature
Ranganath Ratnagiri1, Sai Mallikarjun2
1 Department of Surgical Oncology, Yashoda Cancer Institute, Hyderabad, Andhra Pradesh, India
2 Department of Pathology, Yashoda Hospitals, Hyderabad, Andhra Pradesh, India
|Date of Web Publication||14-Jul-2014|
Division of Surgical Oncology, Yashoda Cancer Institute, Raj Bhavan Road, Somajiguda - 500 082, Hyderabad, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Ancient Schwannomas are rare variants of tumors which arise from the peri-neural Schwann cells. These tumors are termed "ancient" because of the degenerative features acquired with increasing age in these tumors. They are benign, slow growing and usually detected only incidentally or due to local symptoms. Some tumors may demonstrate nuclear atypia, and may be mistakenly termed malignant. Malignant change is usually associated with von Recklinghausen's syndrome in 5% to 18% of cases. Retroperitoneal schwannomas account for only 0.5% to 5% of all cases and are extremely uncommon. They are well encapsulated and recurrences following complete surgical excision are uncommon.
Keywords: Ancient, retroperitoneum, schwannoma
|How to cite this article:|
Ratnagiri R, Mallikarjun S. Retroperitoneal ancient schwannoma: Two cases and review of literature. J Can Res Ther 2014;10:368-70
| > Background|| |
Schwannomas are benign peripheral nerve sheath tumors, which are most common in females, between the second and fifth decades of life.  They occur most often in the head and neck and in the extremities. They are an uncommon cause of a retroperitoneal mass and are classically well-encapsulated and vascular.  Malignant transformation is extremely rare. The term "ancient schwannoma" refers to the degenerative changes, which occur in these tumors with increasing duration (age). , Nuclear atypia may also be present in these tumors and may be mistaken for malignant change.
Complete surgical resection results in cure and recurrences are uncommon.
We describe two cases of retroperitoneal ancient schwannomas treated at our Institute over the past 2 years.
| > CASE REPORTs|| |
A 45-year-old lady presented to us with complaints of left upper quadrant abdominal pain, and perception of a mass in the same site for 3 months. There were no other symptoms. Clinical examination revealed a firm mass in the left hypochondrium with no mobility. A computed tomography (CT) scan revealed a 10 × 8 × 6 cm retroperitoneal tumor, with no evidence of regional or distant metastases [Figure 1]a. The patient underwent a resection of the tumor and had an uneventful post-operative recovery. The gross appearance of the tumor was that of a mixed solid and cystic lesion and the final histopathology was ancient schwannoma [Figure 1]b.
Follow-up: The patient has completed 2 years on follow-up and is clinically asymptomatic and radiologically disease free.
A 50-year-old lady presented to us with left sided flank pain of 1 month duration. Clinical examination was unremarkable. A CT scan revealed a 20 × 15 × 12 cm cystic tumor with solid areas, which seemed to arise from the lower pole of the left kidney. A radical nephrectomy was planned. Intraoperatively, the tumor was found to arise from the retroperitoneum and was infiltrating the left kidney. A radical en bloc resection of the tumor with the left kidney was performed.
Pathology revealed an ancient schwannoma with cystic degeneration and atypical cells [Figure 2].
|Figure 2: H and E stained tumor showing the characteristic Antoni A and B areas (×10)|
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Follow-up: The patient has completed 15 months follow-up and remains disease free.
| > Discussion|| |
Schwannomas or neurilemmomas are benign soft-tissue tumors, which arise from Schwann cells of the peripheral nerve sheaths. They usually arise from sensory nerves; however, motor nerve origin has also been reported.  The most common sites of origin are the head and neck and the extremities.  Retroperitoneal schwannomas are rare and account for 0.3% to 3.2% of these tumors.  Due to the large loose areolar space available, these tumors present late with compression effects and degenerative changes. Classically, therefore, the clinical course is slow and protracted and malignant change is uncommon. They are encapsulated and on histology display the distinctive Antoni A areas, which are highly cellular and Antoni B areas of myxoid stroma.  Spindle shaped cells arranged in palisades, whorls or in parallel lines are characteristic of Antoni A areas, whereas a hypocellular myxoid matrix denotes the Antoni B areas.
Ancient schwannomas are a rare variant described by Ackerman and Taylor in 1951.  They constitute 0.8% of all soft-tissue tumors. They are characterized by distinctive degenerative tumor features such as cystic degeneration, fibrosis, stromal edema, xanthomatous change, and perivascular hyalinization. Degenerative nuclear changes such as pleomorphism, lobulation, and hyperchromasia may also be seen in these tumors.  All these changes have been attributed to the duration of growth ("aging") of the tumor, and consequent vascular insufficiency-hence the term "ancient schwannoma." Despite these changes, ancient schwannomas behave similarly to their conventional counterparts.
On microscopy, ancient schwannomas show areas of cellularity intermixed with myxoid matrix like other conventional schwannomas. The cellular regions however tend to be sclerosed or fibrotic and in time may undergo degenerative changes leading to hematomas and cysts.  Nuclear palisades seen in classic schwannomas are absent. Nuclear atypia and hyperchromasia is common and was also noted in both our cases. Differentiation from malignancy can be made by noting the absence of mitoses and the preservation of cohesive clusters of spindle shaped cells. Flow cytometry assessing the deoxyribonucleic acid ploidy may also help in confirming the benign nature of these tumors.  Diffuse positivity on immunostaining with S 100 is also a feature of these tumors because of their neural origin.
These tumors present with symptoms of compression such as pain, numbness etc., and need surgical excision for establishing a definitive diagnosis. Complete surgical resection of the tumor with preservation of the surrounding structures, if possible will result in cure. 
We have described two cases of an unusual pathological entity, ancient schwannoma arising in the retroperitoneum. These are slow growing, indolent benign tumors, which present with pressure symptoms. Surgical resection results in cure and if there is a suspicion of the diagnosis before surgery, all surrounding structures have to be preserved as recurrences are uncommon.
| > References|| |
|1.||Choudry HA, Nikfarjam M, Liang JJ, Kimchi ET, Conter R, Gusani NJ, et al. Diagnosis and management of retroperitoneal ancient schwannomas. World J Surg Oncol 2009;7:12. |
|2.||Loke TK, Yuen NW, Lo KK, Lo J, Chan JC. Retroperitoneal ancient schwannoma: Review of clinico-radiological features. Australas Radiol 1998;42:136-8. |
|3.||Dahl I. Ancient neurilemmoma (schwannoma). Acta Pathol Microbiol Scand 1977;85:812-8. |
|4.||Jayaraj SM, Levine T, Frosh AC, Almeyda JS. Ancient schwannoma masquerading as parotid pleomorphic adenoma. J Laryngol Otol 1997;111:1088-90. |
|5.||Hughes MJ, Thomas JM, Fisher C, Moskovic EC. Imaging features of retroperitoneal and pelvic schwannomas. Clin Radiol 2005;60:886-93. |
|6.||Graviet S, Sinclair G, Kajani N. Ancient schwannoma of the foot. J Foot Ankle Surg 1995;34:46-50. |
|7.||Ackerman LV, Taylor FH. Neurogenous tumors within the thorax; a clinicopathological evaluation of forty-eight cases. Cancer 1951;4:669-91. |
|8.||Gubbay AD, Moschilla G, Gray BN, Thompson I. Retroperitoneal schwannoma: A case series and review. Aust N Z J Surg 1995;65:197-200. |
[Figure 1], [Figure 2]