OBJECTIVE: To describe the clinical and sonographic characteristics of benign, retroperitoneal, pelvic peripheral-nerve-sheath tumors (PNSTs). METHODS: This was a retrospective study of patients with a benign, retroperitoneal, pelvic PNST who had undergone preoperative ultrasound examination at a single gynecologic oncology center between 1 January 2018 and 31 August 2022. All ultrasound images, videoclips and final histological specimens of benign PNSTs were reviewed side-by-side in order to: describe the ultrasound appearance of the tumors, using the terminology of the International Ovarian Tumor Analysis (IOTA), Morphological Uterus Sonographic Assessment (MUSA) and Vulvar International Tumor Analysis (VITA) groups, following a predefined ultrasound assessment form; describe their origin in relation to nerves and pelvic anatomy; and assess the association between their ultrasound features and histotopography. A review of the literature reporting benign, retroperitoneal, pelvic PNSTs with preoperative ultrasound examination was performed. RESULTS: Five women (mean age, 53 years) with a benign, retroperitoneal, pelvic PNST were identified, four with a schwannoma and one with a neurofibroma, of which all were sporadic and solitary. All patients had good-quality ultrasound images and videoclips and final biopsy of surgically excised tumors, except one patient managed conservatively who had only a core needle biopsy. In all cases, the findings were incidental. The five PNSTs ranged in maximum diameter from 31 to 50 mm. All five PNSTs were solid, moderately vascular tumors, with non-uniform echogenicity, well-circumscribed by hyperechogenic epineurium and with no acoustic shadowing. Most of the masses were round (n = 4 (80%)), and contained small, irregular, anechoic, cystic areas (n = 3 (60%)) and hyperechogenic foci (n = 5 (100%)). In the woman with a schwannoma in whom surgery was not performed, follow-up over a 3-year period showed minimal growth (1.5 mm/year) of the mass. We also summarize the findings of 47 cases of benign retroperitoneal schwannoma and neurofibroma identified in a literature search. CONCLUSIONS: On ultrasound examination, no imaging characteristics differentiate reliably between benign schwannomas and neurofibromas. Moreover, benign PNSTs show some similar features to malignant retroperitoneal tumors. They are solid lesions with intralesional blood vessels and show degenerative changes such as cystic areas and hyperechogenic foci. Therefore, ultrasound-guided biopsy may play a pivotal role in their diagnosis. If confirmed to be benign PNSTs, these tumors can be managed conservatively, with ultrasound surveillance. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Central Military Hospital Prague Czech Republic

Department of Gynecology and Obstetrics Hospital de Braga Braga Portugal

Department of Gynecology and Obstetrics Ospedale Policlinico San Martino and University of Genoa Genova Italy

Department of Neurosurgery and Neuro oncology 1st Faculty of Medicine Charles University Prague Czech Republic

Department of Neurosurgery Neurocenter Regional Hospital Liberec Liberec Czech Republic

Department of Obstetrics and Gynecology Faculty of Medicine Semmelweis University Budapest Hungary

Department of Obstetrics and Gynecology Monash University and Monash Health Clayton Australia

Department of Obstetrics and Gynecology Sheba Medical Center Ramat Gan Israel

Department of Pathology 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Department of Radiology 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Gynecologic Oncology Center Department of Gynecology Obstetrics and Neonatology 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Institute for Women's Health The Medical City Pasig City Philippines

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Ultrasound Obstet Gynecol. 2024 Mar;63(3):435. doi: 10.1002/uog.27561. PubMed

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Fetsch JF, Laskin WB. Soft tissue lesions involving female reproductive organs. In: Blausteinś Pathology of the Female Genital Tract (7th edn), Kurman RJ, Ellenson LH, Ronnett BM (eds). Springer: Switzerland, 2019; 1420.

Goldblum J, Folpe AL, Weiss SW (eds). Enzinger and Weiss's Soft Tissue Tumor (7th edn). Elsevier: London, 2020.

Woodruff JM, Selig AM, Crowley K, Allen PW. Schwannoma (neurilemoma) with malignant transformation. A rare, distinctive peripheral nerve tumor. Am J Surg Pathol 1994; 18: 882-895.

Ningshu L, Min Y, Xieqiao Y, Yuanqing Y, Xiaoqiang M, Rubing L. Laparoscopic management of obturator nerve schwannomas: experiences with 6 cases and review of the literature. Surg Laparosc Endosc Percutan Tech 2012; 22: 143-147.

Strauss DC, Qureshi YA, Hayes AJ, Thomas JM. Management of benign retroperitoneal schwannomas: a single-center experience. Am J Surg 2011; 202: 194-198.

Song JY, Kim SY, Park EG, Kim CJ, Kim DG, Lee HK, Park IY. Schwannoma in the retroperitoneum. J Obstet Gynaecol Res 2007; 33: 371-375.

Antinheimo J, Sankila R, Carpén O, Pukkala E, Sainio M, Jääskeläinen J. Population-based analysis of sporadic and type 2 neurofibromatosis-associated meningiomas and schwannomas. Neurology 2000; 54: 71-76.

Mocellin S. Schwannoma. In: Soft Tissue Tumors: A Practical and Comprehensive Guide to Sarcomas and Benign Neoplasms. Springer International Publishing: Cham, 2021; 711-716.

Takeuchi M, Matsuzaki K, Nishitani H, Uehara H. Ancient schwannoma of the female pelvis. Abdom Imaging 2008; 33: 247-252.

Chikkannaiah P, Boovalli MM, Nathiyal V, Venkataramappa S. Morphological spectrum of peripheral nerve sheath tumors: An insight into World Health Organization 2013 classification. J Neurosci Rural Pract 2016; 7: 346-354.

Chao WT, Liu CH, Chen YJ, Wu HH, Chuang CM, Wang PH. Neurofibroma involving obturator nerve mimicking an adnexal mass: a rare case report and PRISMA-driven systematic review. J Ovarian Res 2018; 11: 14.

Mocellin S. Neurofibroma. In: Soft Tissue Tumors: A Practical and Comprehensive Guide to Sarcomas and Benign Neoplasms. Springer International Publishing: Cham, 2021; 597-604.

Timmerman D, Valentin L, Bourne TH, Collins WP, Verrelst H, Vergote I. Terms, definitions and measurements to describe the sonographic features of adnexal tumors: a consensus opinion from the International Ovarian Tumor Analysis (IOTA) Group. Ultrasound Obstet Gynecol 2000; 16: 500-505.

Van den Bosch T, Dueholm M, Leone FP, Valentin L, Rasmussen CK, Votino A, Van Schoubroeck D, Landolfo C, Installe AJ, Guerriero S, Exacoustos C, Gordts S, Benacerraf B, D'Hooghe T, De Moor B, Brolmann H, Goldstein S, Epstein E, Bourne T, Timmerman D. Terms, definitions and measurements to describe sonographic features of myometrium and uterine masses: a consensus opinion from the Morphological Uterus Sonographic Assessment (MUSA) group. Ultrasound Obstet Gynecol 2015; 46: 284-298.

Fischerova D, Garganese G, Reina H, Fragomeni SM, Cibula D, Nanka O, Rettenbacher T, Testa AC, Epstein E, Guiggi I, Frühauf F, Manegold G, Scambia G, Valentin L. Terms, definitions and measurements to describe sonographic features of lymph nodes: consensus opinion from the Vulvar International Tumor Analysis (VITA) group. Ultrasound Obstet Gynecol 2021; 57: 861-879.

Fischerova D. Ultrasound scanning of the pelvis and abdomen for staging of gynecological tumors: a review. Ultrasound Obstet Gynecol 2011; 38: 246-266.

Bai X, Li Y, Li X, Cao S, Wang L. A case report of primary multiple obturator nerve schwannomas. J Int Med Res 2020; 48: 300060520959490.

Chen CH, Jeng CJ, Liu WM, Shen J. Retroperitoneal schwannoma mimicking uterine myoma. Taiwan J Obstet Gynecol 2009; 48: 176-177.

Choy KT, Kumar K, Ratnapala D. Retroperitoneal schwannoma masquerading as an ovarian cyst. ANZ J Surg 2020; 90: 1820-1822.

Dede M, Yagci G, Yenen MC, Gorgulu S, Deveci MS, Cetiner S, Dilek S. Retroperitoneal benign schwannoma: report of three cases and analysis of clinico-radiologic findings. Tohoku J Exp Med 2003; 200: 93-97.

Deo N, Rayner S, Kalidindi M. A retroperitoneal schwannoma mimicking gynaecological pathology - a case report. J Obstet Gynaecol 2018; 38: 141-142.

Gao C, Zhu FC, Ma BZ, Jia HW, Lu J, Yang J, Guo W, Qi F. A rare case of giant retroperitoneal neurilemmoma. J Int Med Res 2020; 48: 300060520935302.

Garg P, Chawla A, Malhotra R, Narula BS, Thakral A. Sciatic nerve schwannoma at sciatic foramen: importance of transvaginal sonography guided biopsy and magnetic resonance imaging in its diagnosis. J Clin Diagn Res 2018; 12: TD01-TD03.

Gleason T, Le BH, Parthasarathy K, Robinson-Bennett B. Obturator Nerve Schwannoma as a Mimic of Ovarian Malignancy. Case Rep Obstet Gynecol 2017; 2017: 9724827.

Harouachi A, Khomsi N, Aabdi H, Akouh N, Bouhout T, Bennani A, Harroudi TE, Serji B. Surgical management of ancient retroperitoneal schwannoma. Ann Med Surg (Lond) 2022; 79: 103934.

Lee SH, Lee SJ, Lee CS. A rare case of pelvic concurrent schwannoma (neurilemmoma) and neurofibroma. Asian J Surg 2022; 45: 1084-1085.

Li C, Guo L, Hua K. Diagnostic dilemma of retroperitoneal schwannomas encountered in a specialized gynecology hospital. J Invest Surg 2022; 35: 614-619.

Machairiotis N, Zarogoulidis P, Stylianaki A, Karatrasoglou E, Sotiropoulou G, Floreskou A, Chatzi E, Karamani A, Liapi G, Papakonstantinou E, Katsikogiannis N, Courcoutsakis N, Machairiotis C. Pelvic schwannoma in the right parametrium. Int J Gen Med 2013; 6: 123-126.

Maidarti M, Wibawa YS, Garinasih PD, Hellyanti T, Harzif AK, Nuryanto KH. Rare case of pelvic schwannoma mimicking intra-ligamenter uterine fibroid: A case report. Int J Surg Case Rep 2022; 96: 107327.

Okuyama T, Tagaya N, Saito K, Takahashi S, Shibusawa H, Oya M. Laparoscopic resection of a retroperitoneal pelvic schwannoma. J Surg Case Rep 2014; 2014: rjt122.

Padmanaban N, Chandrabose PS, Esakki M, Kirubamani H, Srinivasan C. Gynaecological perspective of schwannoma: a rare pelvic tumour. J Clin Diagn Res 2016; 10: QD03-QD05.

Poojari V, Pai M, Nambiar J, Mathew M. Pelvic schwannoma mimicking as an adnexal mass. Int J Reprod Contracept Obstet Gynecol 2015; 4: 1206-1208.

Santala M MM, Liakka A. Benign presacral schwannoma mimicking pedunculated leiomyoma. J Turkish-German Gynecol Assoc 2007; 8: 90-93.

Santos AJ, Duarte L, Santos SC, Casimiro C. A 68-year-old woman presenting with recurrent abdominal pain and a diagnosis of a presacral retroperitoneal benign schwannoma that mimicked an ovarian tumor on pelvic magnetic resonance imagining. Am J Case Rep 2022; 23: e935985.

Surendrababu NR, Cherian SR, Janakiraman R, Walter N. Large retroperitoneal schwannoma mimicking a cystic ovarian mass in a patient with Hansen's disease. J Clin Ultrasound 2008; 36: 318-320.

Theodosopoulos T, Stafyla VK, Tsiantoula P, Yiallourou A, Marinis A, Kondi-Pafitis A, Chatziioannou A, Boviatsis E, Voros D. Special problems encountering surgical management of large retroperitoneal schwannomas. World J Surg Oncol 2008; 6: 107.

Vilos GA, Vilos AG, Hollett-Caines J, Abu-Rafea B, Jacob GP, Ettler H. Retroperitoneal pelvic tumours in women: diagnostic and therapeutic challenges. Facts Views Vis Obgyn 2020; 11: 299-306.

Yi S, Jin X, Xiong Y, Fu B. Permanent neurological deficit caused by misdiagnosis of a giant intrapelvic sciatic schwannoma: A case report. J Obstet Gynaecol Res 2021; 47: 3413-3417.

Ambrosio M, Testa AC, Moro F, Franchi D, Scifo MC, Rams N, Epstein E, Alcazar JL, Hidalgo JJ, Van Holsbeke C, Burgetova A, Dundr P, Cibula D, Fischerova D. Imaging in gynecological disease (19): clinical and ultrasound features of extragastrointestinal stromal tumors (eGIST). Ultrasound Obstet Gynecol 2020; 56: 749-758.

Fischerova D, Scovazzi U, Sousa N, Hovhannisyan T, Burgetova A, Dundr P, Němejcová K, Bennett R, Vočka M, Frühauf F, Kocian R, Indrielle-Kelly T, Cibula D. Primary retroperitoneal nodal endometrioid carcinoma associated with Lynch syndrome: A case report. Front Oncol 2023; 13: 1092044.

Guo JX, Zhao JG, Bao YN. Adult sacrococcygeal teratoma: A review. Medicine (Baltimore). 2022; 101: e32410.

Ludovisi M, Moro F, Pasciuto T, Di Noi S, Giunchi S, Savelli L, Pascual MA, Sladkevicius P, Alcazar JL, Franchi D, Mancari R, Moruzzi MC, Jurkovic D, Chiappa V, Guerriero S, Exacoustos C, Epstein E, Frühauf F, Fischerova D, Fruscio R, Ciccarone F, Zannoni GF, Scambia G, Valentin L, Testa AC. Imaging in gynecological disease (15): clinical and ultrasound characteristics of uterine sarcoma. Ultrasound Obstet Gynecol 2019; 54: 676-687.

Kalagi D, Bakir M, Alfarra M, Aborayya A, Anwar I. Two unusual presentations of presacral schwannoma; a case series. Int J Surg Case Rep 2019; 61: 165-168.

Transatlantic Australasian Retroperitoneal Sarcoma Working Group. Intercontinental collaborative experience with abdominal, retroperitoneal and pelvic schwannomas. Br J Surg 2020; 107: 452-463.

Nakashima J, Ueno M, Nakamura K, Tachibana M, Baba S, Deguchi N, Tazaki H, Murai M. Differential diagnosis of primary benign and malignant retroperitoneal tumors. Int J Urol 1997; 4: 441-446.

Jha A, Gupta P, Wahab S, Gupta G, Zaidi SY. Role of ultrasonography in detection of renal artery pseudoaneurysm caused by retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1. J Med Ultrason 2014; 41: 87-91.

Reynolds DL, Jr., Jacobson JA, Inampudi P, Jamadar DA, Ebrahim FS, Hayes CW. Sonographic characteristics of peripheral nerve sheath tumors. AJR Am J Roentgenol 2004; 182: 741-744.

Valeyrie-Allanore L, Ismaïli N, Bastuji-Garin S, Zeller J, Wechsler J, Revuz J, Wolkenstein P. Symptoms associated with malignancy of peripheral nerve sheath tumours: a retrospective study of 69 patients with neurofibromatosis 1. Br J Dermatol 2005; 153: 79-82.

Yamanaka R, Hayano A. Radiation-induced malignant peripheral nerve sheath tumors: a systematic review. World Neurosurg 2017; 105: 961-970.e8.

Pennington Z, Reinshagen C, Ahmed AK, Barber S, Goodwin ML, Gokaslan Z, Sciubba DM. Management of presacral schwannomas-a 10-year multi-institutional series. Ann Transl Med 2019; 7: 228.

Hassan I, Wietfeldt ED. Presacral tumors: diagnosis and management. Clin Colon Rectal Surg 2009; 22: 84-93.

Takatera H, Takiuchi H, Namiki M, Takaha M, Ohnishi S, Sonoda T. Retroperitoneal schwannoma. Urology 1986; 28: 529-531.

Crist J, Hodge JR, Frick M, Leung FP, Hsu E, Gi MT, Venkatesh SK. Magnetic resonance imaging appearance of schwannomas from head to toe: a pictorial review. J Clin Imaging Sci 2017; 7: 38.

Bhargava R, Parham DM, Lasater OE, Chari RS, Chen G, Fletcher BD. MR imaging differentiation of benign and malignant peripheral nerve sheath tumors: use of the target sign. Pediatr Radiol 1997; 27: 124-129.

Jee WH, Oh SN, McCauley T, Ryu KN, Suh JS, Lee JH, Park JM, Chun KA, Sung MS, Kim K, Lee YS, Kang YK, Ok IY, Kim JM. Extraaxial neurofibromas versus neurilemmomas: discrimination with MRI. AJR Am J Roentgenol 2004; 183: 629-633.

Wasa J, Nishida Y, Tsukushi S, Shido Y, Sugiura H, Nakashima H, Ishiguro N. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR Am J Roentgenol 2010; 194: 1568-1574.

Hughes MJ, Thomas JM, Fisher C, Moskovic EC. Imaging features of retroperitoneal and pelvic schwannomas. Clin Radiol 2005; 60: 886-893.

Hayasaka K, Tanaka Y, Soeda S, Huppert P, Claussen CD. MR findings in primary retroperitoneal schwannoma. Acta Radiol 1999; 40: 78-82.

Li CS, Huang GS, Wu HD, Chen WT, Shih LS, Lii JM, Duh SJ, Chen RC, Tu HY, Chan WP. Differentiation of soft tissue benign and malignant peripheral nerve sheath tumors with magnetic resonance imaging. Clin Imaging 2008; 32: 121-127.

Berger-Richardson D, Burtenshaw SM, Ibrahim AM, Gladdy RA, Auer R, Beecroft R, Dickson BC, Purgina B, Ambacher K, Nessim C, Swallow CJ. Early and late complications of percutaneous core needle biopsy of retroperitoneal tumors at two tertiary sarcoma centers. Ann Surg Oncol 2019; 26: 4692-4698.

Szabó G, Madár I, Hudelist G, Arányi Z, Turtóczki K, Rigó J, Jr., Ács N, Lipták L, Fancsovits V, Bokor A. Visualization of sacral nerve roots and sacral plexus on gynecological transvaginal ultrasound: feasibility study. Ultrasound Obstet Gynecol 2023; 62: 290-299.

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