Endoscopy 2010; 42: E296
DOI: 10.1055/s-0030-1255786
Unusual cases and technical notes

© Georg Thieme Verlag KG Stuttgart · New York

Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of retroperitoneal schwannoma

S.  Hijioka1 , A.  Sawaki1 , N.  Mizuno1 , K.  Hara1 , M.  A.  Mekky2 , V.  Bhatia3 , W.  Hosoda4 , Y.  Yatabe4 , Y.  Shimizu5 , K.  Tamada6 , Y.  Niwa7 , K.  Yamao1
  • 1Department of Gastroenterology, Aichi Cancer Center Hospital, Nagoya, Japan
  • 2Department of Tropical Medicine and Gastroenterology, Assiut University Hospital, Assiut, Egypt
  • 3Department of Medical Hepatology, Institute of Liver and Biliary Sciences, Delhi, India
  • 4Department of Genetic Pathology and Molecular Diagnostics, Aichi Cancer Center Hospital, Nagoya, Japan
  • 5Department of Gastroenterological Surgery, Aichi Cancer Center Hospital, Nagoya, Japan
  • 6Department of Gastroenterology, Jichi Medical University, Tochigi, Japan
  • 7Department of Endoscopy, Aichi Cancer Center Hospital, Nagoya, Japan
Further Information

Publication History

Publication Date:
26 November 2010 (online)

Schwannoma is a rare peripheral nerve sheath tumor that is difficult to diagnose by imaging features alone. Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) with specific immunohistochemical (IHC) staining may be the only tool to obtain a diagnostic sample from such lesions. There are only a few case reports describing EUS-FNA diagnosis of retroperitoneal Schwannoma [1] [2]. In this report, we describe four cases (three males; mean age: 54.5 ± 16.4 years) with retroperitoneal Schwannoma, in whom the diagnosis was achieved with EUS-FNA and adjunctive IHC staining.

All lesions were well demarcated, and had a rounded contour ([Fig. 1 a]).

Fig. 1 Imaging findings and histopathological features. a Contrast enhanced computed tomography (CT) scan showing well-demarcated low density mass in the retroperitoneal region. b Endoscopic ultrasound image showing a fine needle inserted into the mass (arrow). c Spindle cells on cellblock sections, without any mitosis (hematoxylin and eosin stain, original magnification × 400). d Immunohistochemical S-100 positive staining (magnification × 400).

The mean size of the lesions on EUS was 23.7 ± 3.6 mm. EUS-FNA was successfully performed with a 22-gauge needle in all cases ([Fig. 1 b]), with a sufficient yield for both cytological and cellblock analysis. The median number of needle passes was 2.5 (range 2 – 3). The cellblock analysis revealed bland proliferation of spindle cells with a palisading appearance and wavy fibrillar architecture ([Fig. 1 c]). Further evaluation with IHC revealed negative staining for actin, CD34, CD-117, and strong positive staining for S-100 antibody in all cases ([Fig. 1 d]). Further evaluation of the cellular proliferative activity was studied with Ki-67 staining, and a low proliferation rate (Ki-67 < 5 %) was reported in all cases, supporting the benign nature of the lesions.

We recommended conservative follow-up for our patients rather than surgical resection, because all of the patients were asymptomatic and there were no mitotic figures on FNA, with a low Ki-67 index in all the aspirates. It is worth noting that most reports have stressed on complete surgical resection as the appropriate management of retroperitoneal schwannomas [3] [4]. Our view is that the morbidity associated with surgical resection is not justified in these benign lesions, and the use of EUS-FNA to establish the diagnosis may help in avoiding unnecessary surgery.

Competing interests: None



S. Hijioka

Department of Gastroenterology
Aichi Cancer Center Hospital

1-1 Kanokoden
Aichi 464-8681

Fax: +81-52-7642963

Email: rizasusu@aichi-cc.jp