Soft tissue
Peripheral nerve
Other benign
Solitary circumscribed neuroma
Board of reviewers: Carina Dehner, M.D., Ph.D.
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Last author update: 17 October 2024
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PubMed Search: Solitary circumscribed neuroma
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Videos | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Jiang J, Chung M, Huang YY. Solitary circumscribed neuroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuesolitarycircneuroma.html. Accessed November 28th, 2024.
Definition / general
- Solitary circumscribed neuroma (SCN) is a benign, slow growing proliferation of Schwann cells and nerve axons within the perineurium
Essential features
- Benign, slow growing proliferation of peripheral nerve cells
- Small (< 1 cm), solitary, skin colored papulonodule on the face of a middle aged adult
- Surgical excision is usually curative and SCNs rarely recur (even with incomplete excision) (Int J Surg Pathol 2019;27:506)
Terminology
- Also known as palisaded encapsulated neuroma (PEN)
ICD coding
- ICD-10: D36.10 - benign neoplasm of peripheral nerves and autonomic nervous system, unspecified
Epidemiology
- Typically found in middle aged adults
- No difference in incidence between men and women
- Rarely, multiple SCNs can be associated with MEN2B syndrome (Am J Dermatopathol 2014;36:562)
- Rarely, multiple acral SCNs can be associated with PTEN mutations (Am J Dermatopathol 2014;36:562, Pediatr Dermatol 2017;34:e219)
Sites
- Commonly found on the head and neck (especially near mucocutaneous junctions) and oral cavity (Int J Surg Pathol 2019;27:506, J Yeungnam Med Sci 2022;39:168)
- Less often found on trunk, extremities and genitalia (Cureus 2016;8:e726, J Dent Sci 2021;16:1041, Dermatol Online J 2020;26:13030/qt3b10r3zk)
- Multiple acral PENs can be associated with PTEN mutations (Pediatr Dermatol 2017;34:e219, J Cutan Pathol 2022;49:82)
Pathophysiology
- Poorly understood at this time
- Thought to be reactive but are often reported without any history of inciting trauma (Cutis 2013;92:167)
- Has not been found to be associated with malignancies
Etiology
- Largely unknown
- Benign neoplasm that is thought to be idiopathic or reactive in nature (Cutis 2013;92:167, J Yeungnam Med Sci 2022;39:168)
- Rarely, multiple SCNs can be associated with MEN2B (Am J Dermatopathol 2014;36:562)
- Rarely, multiple acral SCNs can be associated with PTEN mutations (Pediatr Dermatol 2017;34:e219, J Cutan Pathol 2022;49:82)
Clinical features
- Usually solitary
- Small (< 1 cm), firm, rubbery, skin colored papulonodules, often near mucocutaneous junctions
- Generally asymptomatic
- Reference: VisualDx: Palisaded Encapsulated Neuroma [Accessed 21 August 2024]
Diagnosis
- Definitive diagnosis requires skin biopsy with histopathologic evaluation
Prognostic factors
- Benign tumor but can be cosmetically bothersome
- Surgical excision is curative
- Rarely recurs, even with incomplete excision (J Yeungnam Med Sci 2022;39:168)
- Acral plexiform lesions and multiple lesions can rarely be associated with underlying genetic mutations (Am J Dermatopathol 2014;36:562, Pediatr Dermatol 2017;34:e219, J Cutan Pathol 2022;49:82)
Case reports
- 30 year old woman with painful nodule on the right cheek (Dermatol Online J 2020;26:13030/qt11r6714r)
- 30 year old man with exophytic mass on the hard palate (Clin Case Rep 2023;11:e8212)
- 50 year old man with dome shaped papule on the upper lip (JAAD Case Rep 2024;49:1)
- 52 year old man with solitary papule on the glans penis (Dermatol Online J 2020;26:13030/qt3b10r3zk)
- 63 year old woman with painless cystic nodule on the lower lip (J Yeungnam Med Sci 2022;39:168)
Treatment
- Surgical excision is curative and recurrence is rare (even with incomplete excision) (J Yeungnam Med Sci 2022;39:168)
Clinical images
Images hosted on other servers:
Solitary skin colored papule
Vague vascularity on dermoscopy
Exophytic mass on palate
Gross description
- Firm, well circumscribed, gray-white, sphere to ovoid papule (Am J Surg Pathol 1989;13:574)
Microscopic (histologic) description
- Well circumscribed dermal tumor
- Thin to incomplete perineural connective tissue capsule surrounding the tumor
- Cells are arranged in fascicles or small nodules
- Distinct artificial cleft and cracks between the fascicles
- Compositional cells are narrow, elongated and wavy with tapered ends
- Multinodular or plexiform growth pattern is uncommon (J Cutan Pathol 1993;20:34)
- Rarely, epithelioid cells are present (Histopathology 1992;20:439)
Microscopic (histologic) images
Contributed by Yuan Yu Huang, M.D.
Well circumscribed dermal nodule
Distinct clefting artifact
Cytology and background features
Superficial dermal proliferation
Distinct clefting artifact
Small dermal papule
Sparse peripheral capsule
S100
EMA
Neurofilament
Positive stains
- S100 (strong and diffuse staining) (Ophthalmic Plast Reconstr Surg 2011;27:e35)
- EMA (positive only in the perineurial cells of the peripheral capsule) (Am J Surg Pathol 1989;13:574)
- Neurofilament (focal positivity in intermingling axons) (Ophthalmic Plast Reconstr Surg 2011;27:e35)
Negative stains
Videos
Palisaded encapsulated neuroma (solitary circumscribed neuroma)
Sample pathology report
- Skin, left cheek, shave biopsy:
- Solitary circumscribed neuroma (palisaded encapsulated neuroma) (see comment)
- Comment: Sections show a well circumscribed dermal nodule with peripheral thin connective tissue capsule. The proliferation is composed of wavy spindle cells in nests and fascicles with intermittent cleft-like spaces.
Differential diagnosis
- Schwannoma:
- More defined and developed capsule
- Displays a varied cell density (Antoni A and Antoni B)
- Lacks the clefting artifact of solitary circumscribed neuroma
- Neurofibroma:
- Lacks capsule
- Heterogeneous appearance due to mixed composition of Schwann cells, fibroblasts, collagen fibers and mast cells
- Weaker S100 staining
- Traumatic neuroma:
- Occurs at site of previous trauma or surgery
- Disorganized organization of nerve bundles
- Also has clefting artifacts
- Has a background fibrotic stroma
- Leiomyoma:
Board review style question #1
Which of the following is true of the entity shown in the image above?
- It is a well circumscribed proliferation composed of cigar shaped spindle cells
- It is commonly seen in the oral cavity
- It is often associated with underlying neurofibromatosis
- It often recurs after surgical excision
Board review style answer #1
B. It is commonly seen in the oral cavity. The image above shows a solitary circumscribed neuroma (palisaded encapsulated neuroma). They are commonly seen on the head and neck and oral cavity. Answer A is incorrect because this is a well circumscribed proliferation composed of wavy spindled Schwannian cells (cigar shaped spindle cells would refer to smooth muscle cells). Answer D is incorrect because they are benign neoplasms and excision is curative, with low risk of recurrence. Answer C is incorrect because rarely, multiple solitary circumscribed neuromas are associated with underlying neurofibromatosis.
Comment Here
Reference: Solitary circumscribed neuroma
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Reference: Solitary circumscribed neuroma
Board review style question #2
Which of the following stains is diffusely positive in solitary circumscribed neuroma (SCN)?
- Cytokeratin
- EMA
- S100
- SMA
Board review style answer #2
C. S100. Solitary circumscribed neuroma is diffusely positive for S100. Answer B is incorrect because there is only focal positivity in the peripheral perineural cells of the thin capsule. Answers A and D are incorrect because SCN is negative for cytokeratin and SMA.
Comment Here
Reference: Solitary circumscribed neuroma
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Reference: Solitary circumscribed neuroma
