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Year : 2022  |  Volume : 15  |  Issue : 1  |  Page : 134-135  

Plexiform schwannomas an update

Department of Pathology, Sri Devaraj Urs Medical College, Kolar, Karnataka, India

Date of Submission13-Aug-2020
Date of Decision10-Sep-2020
Date of Acceptance21-Sep-2020
Date of Web Publication12-Jul-2021

Correspondence Address:
Subhashish Das
C/o. Department of Pathology, Sri Devaraj Urs Medical College, Tamaka, Kolar, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjdrdypu.mjdrdypu_440_20

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How to cite this article:
Das S. Plexiform schwannomas an update. Med J DY Patil Vidyapeeth 2022;15:134-5

How to cite this URL:
Das S. Plexiform schwannomas an update. Med J DY Patil Vidyapeeth [serial online] 2022 [cited 2022 Aug 11];15:134-5. Available from: https://www.mjdrdypv.org/text.asp?2022/15/1/134/321218

Schwannomas exhibit histologic features that may overlap with those of benign and malignant peripheral nerve sheath tumors (MPNSTs). This can be the challenging in making accurate histopathological diagnosis there by influence clinical management.[1]

Schwannomas show an interesting histologic variety despite being composed of a limited array of cellular constituents. Key issue for the pathologist is a definitive diagnosis in this histologic diversity for better management. Peripheral nerve sheath neoplasms exhibit histologic features that overlap with those of many other benign and malignant soft-tissue tumors.[2] The correct diagnosis relies mainly on histologic findings and immunohistochemistry profile, but ultrastructural studies can be used in difficult cases. Key issue for the pathologist includes distinguishing schwannomas from neurofibromas and MPNSTs from cellular schwannoma or neurofibromas Plexiform schwannoma is a rare variant of schwannoma that accounts for only 5% of all schwannomas and typically shows a plexiform or multinodular growth pattern. It was first described by Harkin and Reed in 1978, and very few cases had since been reported.[3]

It is believed that these lesions arise from proliferation of Schwann cells at a point inside the perineurium, which causes a displacement and compression of the surrounding normal nerve tissue and trauma and neurofibromatosis type 2 are well-recognized risk factors for these lesions.[4]

Differential diagnosis of plexiform schwannoma poses a challenge and includes mucocele, granular cell tumor, lipoma, hemangioma, eosinophilic granuloma, epidermoid and dermoid cysts, epithelial hyperplasia, and benign salivary gland tumors. In some cases, glandular malignant processes, squamous cell carcinoma, sarcomas, and MPNSTs may share similar clinical features plexiform schwannoma from plexiform neurofibromas and MPNSTs because plexiform schwannoma follows a benign clinical course, with complete surgical excision being curative. Plexiform schwannoma can have a multinodular or plexiform appearance, although the term has been used interchangeably by many researchers.[5]

Solitary plexiform schwannomas occur in patients with no significant predisposing factor, however, multiple tumors are more frequent in individuals with neurofibromatosis Type II, schwannomatosis, Gorlin–Koutlas syndrome, and patients with positive family history or history of trauma.[6]

No sex predilection has been reported for plexiform schwannoma. Malignant transformation of this benign neoplasm is very rare. There are some case reports of benign solitary schwannomas with a consequent malignant transformation.[7]

Although plexiform schwannoma has a superficial resemblance to the plexiform neurofibroma characterized by multinodular growth, it is composed purely of Schwann cells with nuclear palisading and verocay bodies without myxoid changes of stroma. Whereas S100 protein staining identifies a purely and strongly positive Schwann cell population in plexiform schwannoma, variable expression of this antigen is observed in plexiform neurofibroma.[8] To exclude the malignant counterpart, the combination of pathologic findings (cellularity, mitotic activity, and at typia), as well as immunohistochemical study for S100 protein (most MPNSTs show negative or weak staining) should be considered.[9]

  References Top

Ioannou M, Papanastassiou I, Iakowidou I, Kottakis S, Demertzis N. Plexiform schwannoma of the posterior tibial nerve: A case report. Cases J 2009;2:8392.  Back to cited text no. 1
Berg JC, Scheithauer BW, Spinner RJ, Allen CM, Koutlas IG. Plexiform schwannoma: a clinicopathologic overview with emphasis on the head and neck region. Hum Pathol 2008;39:633-40.  Back to cited text no. 2
Rodriguez FJ, Folpe AL, Giannini C, Perry A. Pathology of peripheral nerve sheath tumors: Diagnostic overview and update on selected diagnostic problems. Acta Neuropathol 2012;123:295-319.  Back to cited text no. 3
Neurilemmoma. Medscape; August 18, 2016. Avilable from: https://emedicine.medscape.com/article/1256405-overview [Last accessed on 2016 Oct 07].  Back to cited text no. 4
Patterson JW. Neural and neuroendocrine tumors. In: Patterson JW, editor. Weedon's Skin Pathology. 4th ed. London: Churchill Livingstone; 2016. p. 1041-67.  Back to cited text no. 5
Woodruff JM, Selig AM, Crowley K, Allen PW. Schwannoma (neurilemoma) with malignant transformation. A rare, distinctive peripheral nerve tumor. Am J Surg Pathol 1994;18:882-95.  Back to cited text no. 6
Nayler SJ, Leiman G, Omar T, Cooper K. Malignant transformation in a schwannoma. Histopathology 1996;29:189-92.  Back to cited text no. 7
Peng X, Chen L, Du H, Lai Y, Li F, Zou X. Malignant transformation of benign intraosseous schwannoma in the cervical spine: A case report with an immunohistochemical study. Int Surg 2011;96:337-44.  Back to cited text no. 8
Parihar A, Verma S, Suri T, Agarwal A, Bansal K, Gupta R. Plexiform schwannoma of lumbar region. APSP J Case Rep 2015;6:16.  Back to cited text no. 9


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