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 Table of Contents  
Year : 2022  |  Volume : 12  |  Issue : 5  |  Page : 232-234

Solitary neurofibroma of the psoas muscle: An unusual location

1 Department of Surgery, Care Multispecialty Hospital, Vadodara, Gujarat, India
2 Department of Pathology, Care Multispecialty Hospital, Vadodara, Gujarat, India

Date of Submission30-Mar-2022
Date of Decision10-May-2022
Date of Acceptance11-May-2022
Date of Web Publication31-Oct-2022

Correspondence Address:
Himani-Tiwari Chaturvedi
Department of Pathology, Care Multispecialty Hospital, Maneja, Vadodara, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/cmrp.cmrp_32_22

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Neurofibroma is a benign peripheral nerve sheath tumour usually present on superficial tissues of the head and trunk. Retroperitoneal location is extremely rare for neurofibroma and comprises only 1% of all retroperitoneal tumours. It can be solitary or associated with the genetic disorder, von Recklinghausen's disease or neurofibromatosis type-1. Magnetic resonance imaging (MRI) is the gold standard modality for imaging retroperitoneal tumours because it provides a better definition and specificity in the evaluation of the location, extension, and composition of the lesion. Here, we report the case of a 30-year-old man affected by retroperitoneal solitary neurofibroma of the psoas muscle, but not associated with von Recklinghausen's disease. MRI showed a well-defined lobulated retroperitoneal lesion noted within the right psoas muscle. Complete surgical excision of the tumour was performed, and the diagnosis of neurofibroma was made through histological and immunohistochemical examination.

Keywords: Neurofibroma, peripheral nerve sheath tumour, psoas muscle, retroperitoneal tumour

How to cite this article:
Chaturvedi C, Chaturvedi HT. Solitary neurofibroma of the psoas muscle: An unusual location. Curr Med Res Pract 2022;12:232-4

How to cite this URL:
Chaturvedi C, Chaturvedi HT. Solitary neurofibroma of the psoas muscle: An unusual location. Curr Med Res Pract [serial online] 2022 [cited 2023 Feb 2];12:232-4. Available from: http://www.cmrpjournal.org/text.asp?2022/12/5/232/359938

  Introduction Top

Retroperitoneal nerve sheath tumours are extremely rare group tumours with non-specific clinical presentation. Neurofibroma is a benign peripheral nerve sheath tumour, mainly present on the skin of the trunk and head. It can be solitary or associated with von Recklinghausen's disease or neurofibromatosis type-1 (NF-1). Solitary neurofibroma of retroperitoneal space, without any other sign of von Recklinghausen's disease has rarely been reported.[1],[2],[3],[4] Here, we report an unusual case of solitary neurofibroma of the psoas muscle in a 30-year-old male.

  Case Report Top

A 30-year-old male with no known history of any surgical and medical illness presented with a complaint of vague abdominal pain, off and on, for one year. General clinical examination was grossly unremarkable and palpation of the abdomen was normal except mild tenderness in the right lumbar region.

Haematological and biochemical investigations were within normal limits. Ultrasound-guided fine-needle aspiration cytology (FNAC) was performed and suggestive of myxoma and neurofibroma. Magnetic resonance imaging (MRI) showed a well-defined lobulated altered signal intensity lesion, measuring 4.0 cm × 5.4 cm × 6.7 cm in size, within the right psoas muscle and bulging into the right perinephric space abutting the right kidney. No extension of the lesion was noted within the adjacent neural foramina or central canal [Figure 1]. Complete surgical resection of the retroperitoneal mass was done through the right oblique lumbar incision. The right psoas in the retroperitoneal cavity was exposed by meticulous peritoneal reflection. Keeping in view the possibility of malignancy, the lesion was removed in totality with margins of the psoas muscle all around. No association of lesion was seen with any nerve or spinal roots. Adequate haemostasis was achieved, and layered closure was done without a drain [Figure 2]a and [Figure 2]b. Macroscopically, the lesion was well-circumscribed greyish yellow mass with attached muscle, soft in consistency, measuring about 6.8 cm × 5.7 cm × 4.0 cm in size, bigger than what was evident on MRI [Figure 2]c.
Figure 1: (a) T2 weight axial and (b) STIR coronal view MRI image shows a well-defined lobulated lesion (→) in the right psoas muscle. MRI: Magnetic resonance imaging

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Figure 2: (a) Intraoperative view of tumour (→) with in the psoas muscle, (b) complete excision of tumour with safe margin of the psoas muscle, (c) macroscopic image of resected mass

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Microscopic examination revealed a well-circumscribed lesion composed of loosely arranged scattered tumour cells with wavy nuclei, pointed at both ends, with the fibrillar and myxoid background. Immunohistochemical staining was positive for S-100, which confirmed the diagnosis of neurofibroma [Figure 3].
Figure 3: (a) Histopathological image shows spindle cells with wavy nuclei in fibromyxoid stroma (H and E ×400 magnification), (b) immunohistochemistry shows diffuse positivity for S-100 (×400 magnification)

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The postoperative period was uneventful and the patient was discharged from hospital on the 3rd post-operative day. No neuropathy or radiculopathy was observed in the post-operative period. He has been regularly followed up for six months and is doing well.

  Discussion Top

Primary retroperitoneal tumours are an extremely rare group of tumours and 10%–20% are neurogenic tumours. Neurofibroma is very rare and contributes to only 1% retroperitoneal nerve sheath tumours.[3],[4],[5]

Neurofibromas are benign nerve sheath tumours usually found on the skin of the trunk and the head. They are often multiple, plexiform, and found in association with NF-1. However, they can also develop in patients without any hereditary disorder as solitary tumours of deep organs. Neurofibroma of the retroperitoneum involving the psoas muscle is exceedingly rare.[1],[3],[5] Retroperitoneal neurofibromas are non-encapsulated and most common in the second to fourth decade with slight male predilection. Almost all plexiform or multiple and 30% of solitary neurofibromas are associated with NF-1.[4],[5] There are five categories of abdominal neoplasms in NF-1: neurogenic, neuroendocrine, non-neurogenic gastrointestinal mesenchymal, embryonal and miscellaneous.[6] The present case was not consistent with NF-1.

Relatively unrestricted growth of retroperitoneal masses usually leads to delayed diagnosis.[2] Clinical symptoms are usually non-specific, and the most common presentation is vague and dull abdominal pain due to compression. A variety of other symptoms may occur depending on the location, including asymptomatic abdominal mass, flank pain, back pain, nausea, vomiting, constipation, recurrent renal colic pain and other neurologic symptoms like neuralgic pain.[1],[2],[6],[7],[8] Bilateral neurofibromas of the psoas muscle along with ulcerative colitis, may present as gastrointestinal bleeding.[9]

Diagnosis of a retroperitoneal neurofibroma is difficult to establish preoperatively because of non-specific clinical symptoms. Standard methods for the evaluation of these lesions are computed tomography (CT) and MRI. A CT scan provides valuable information, but MRI is accepted better for the diagnosis of most soft tissue tumours. MRI offers higher resolution and definition, and it allows more specificity in evaluation of the location, extensions and composition of lesions which can help in surgical planning.[5],[8],[10]

Fine needle aspiration cytology and CT-guided biopsy could be deceptive or inconclusive, so should not be relied upon to obtain a correct diagnosis of retroperitoneal tumours.[5],[10] Definitive diagnosis will be possible only by histopathological evaluation.

Histologically neurofibroma consists of the proliferation of spindle cells with wavy nuclei without pleomorphism arranged haphazardly in a fibromyxoid background. It also expresses positive staining for S100 protein on immunohistochemical staining, which clearly differentiates it from myxoma.[1] Complete surgical excision is recommended treatment of choice for retroperitoneal nerve sheath tumours because malignancy cannot be excluded preoperatively, and residual disease may have the potential to develop recurrence or malignant transformation.[4],[7],[10]

  Conclusion Top

Retroperitoneal solitary neurofibroma of the psoas muscle is an extremely rare benign tumour arising from the peripheral nerve sheath. A meticulous pre-operative diagnosis is vital for appropriate management. Surgery ensures a good long-term prognosis with low chances of recurrence. Histopathology is the hallmark in the neurofibroma but should always be confirmed by immunohistochemistry.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Dąbkowski K, Marlicz W, Kaseja K, Sawicki M, Waloszczyk P, Starzyńska T. Solitary retroperitoneal neurofibroma: Not as small as it seems. Pol Arch Intern Med 2017;127:701-2.  Back to cited text no. 1
Ishikawa J, Kamidono S, Maeda S, Sugiyama T, Hara I, Takechi Y, et al. Solitary retroperitoneal neurofibroma: A case report. Hinyokika Kiyo 1989;35:1157-60.  Back to cited text no. 2
Scali EP, Chandler TM, Heffernan EJ, Coyle J, Harris AC, Chang SD. Primary retroperitoneal masses: What is the differential diagnosis? Abdom Imaging 2015;40:1887-903.  Back to cited text no. 3
Dayan D, Abu-Abeid S, Kuriansky J, Lahat G, Sagie B. Rare primary retroperitoneal neoplasms. Isr Med Assoc J 2020;22:53-9.  Back to cited text no. 4
Makhoul E, Kamel R, Hanna N. Schwannoma of the psoas: An unusual cause of abdominal pain. Arab J Gastroenterol 2017;18:44-6.  Back to cited text no. 5
Levy AD, Patel N, Dow N, Abbott RM, Miettinen M, Sobin LH. From the archives of the AFIP: Abdominal neoplasms in patients with neurofibromatosis Type 1: Radiologic-pathologic correlation. Radiographics 2005;25:455-80.  Back to cited text no. 6
Njoumi N, Elabsi M, Attolou G, Elouazzani H, Elalami FH, Chkoff MR. Solitary preperitoneal neurofibroma: A case report. BMC Res Notes 2015;8:115.  Back to cited text no. 7
Guha D, Davidson B, Nadi M, Alotaibi NM, Fehlings MG, Gentili F, et al. Management of peripheral nerve sheath tumors: 17 years of experience at Toronto Western Hospital. J Neurosurg 2018;128:1226-34.  Back to cited text no. 8
Tavakkoli H, Asadi M, Mahzouni P, Foroozmehr A. Ulcerative colitis and neurofibromatosis type 1 with bilateral psoas muscle neurofibromas: A case report. J Res Med Sci 2009;14:261-5.  Back to cited text no. 9
Guz BV, Wood DP, Jr., Montie JE, Pontes JE. Retroperitoneal neural sheath tumors: Cleveland clinic experience. J urol 1989;142:1434-7.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]


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