Solitary Circumscribed Neuroma

Definition

• Cutaneous nodular neuroma consisting of Schwann cells and numerous axons with a delicate perineurial capsule

Alternate/Historical Names

• Palisaded encapsulated neuroma

Diagnostic Criteria

• Usually a solitary nodule
  • Occasionally multinodular or plexiform
    • May have hyalinized vessels if plexiform
• Circumscribed dermal or submucosal lesion
  • Most only poorly and partially encapsulated (if at all)
  • Helpful retraction artifact from the surrounding dermis
• Comprised predominantly of spindled Schwann cells forming bundles/micro-fascicles
  • Vague palisading may be present
    • Generally no significant, well formed palisading
    • Nuclear regimentation into Verocay bodies is occasionally present
  • Mitotic activity and significant atypia are uncommon
• Contain numerous axons throughout the nodule
• Approximately 90% affect the face, lips or oral cavity

Jason Karamchandani MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates : 11/13/10

Supplemental Studies

Immunohistochemistry:

• S100 positive
• GFAP negative
• EMA, Glut-1 and Claudin-1 positive in occasional cells at the periphery
  • May be faint
• Neurofilament identifies axons present throughout the lesion

Clinical

• Usually cutaneous
• Approximately 90% affect the face, nose, cheek, forehead, and lips
• Peak age 50-70s
• Typically range in size from 1-15mm
• Excision is curative

Differential Diagnosis

• Schwannoma
• Neurofibroma
• Mucosal neuroma / neuromatosis
• Traumatic neuroma
• Leiomyoma

Solitary Circumscribed (Palisaded Encapsulated) Neuroma	Schwannoma
90% of lesions affect the face	Can occur anywhere
Common in the dermis	Uncommon in the dermis
Peripheral, delicate EMA positivity	Completely surrounded by perineurial capsule
GFAP negative	Can be GFAP positive
Axons throughout the lesion	Axons, when present, are typically peripheral / subcapsular
No organization into Antoni A and Antoni B areas	Feature Antoni A and Antoni B areas

Solitary Circumscribed (Palisaded Encapsulated) Neuroma	Neurofibroma
90% of lesions affect the face	Can occur anywhere
Usually solitary	Frequently multiple
Delicate EMA peripheral positivity	No peripheral perineurial capsule
GFAP negative	Can be GFAP positive
Rare mast cells	Frequent mast cells
Predominantly composed of Schwann cells	Contain neural fibroblasts and fibrillary collagen
No known familial association	May be associated with neurofibromatosis

Both contain axons throughout

Solitary Circumscribed (Palisaded Encapsulated) Neuroma	Mucosal Neuroma/Neuromatosis
Usually solitary	Frequently multiple
Lacks structure of normal nerves	Hyperplastic normal nerves
Perineurium present at the periphery	Perineurium present around individual nerve bundles
No known familial association	Associated with MEN2b

Traumatic Neuroma	Solitary Circumscribed (Palisaded Encapsulated) Neuroma
Can occur anywhere	90% of lesions affect the face
Usually located in soft tissue	Usually located in dermis
History of trauma or surgery	No history of prior trauma or surgery
Can have irregular margin	Generally circumscribed
Numerous well formed small nerve twigs	Random proliferation of Schwann cells and axons
EMA+ perineurium surrounds individual nerve twigs	EMA+ perineurium restricted to periphery of the entire neuroma

Solitary Circumscribed (Palisaded Encapsulated) Neuroma	Leiomyoma
Composed of S100 positive schwann cells	Composed of actin/desmin positive smooth muscle cells

Lists

Tumors of Peripheral Nerves

• Granular cell tumor
• Inflammatory pseudotumor
• Localized interdigital neuroma (Morton neuroma)
• Neural fibrolipoma
• Neurofibroma
• Neuromuscular choristoma
• Neurothekeoma
• Nerve cyst
• Nerve sheath myxoma
• Malignant peripheral nerve sheath tumor
• Pacinian neuroma
• Perineurioma
• Schwannoma
• Solitary circumscribed (palisaded encapsulated} neuroma
• Traumatic neuroma
  

Bibliography

• Scheithauer BW, Woodruff JM, Erlandson RA. Tumors of the Peripheral Nervous System, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 24, 1999.
• Weiss SW, Goldblum JR, Enzinger FM. Enzinger and Weiss' soft tissue tumors. 5th ed. Philadelphia, PA: Mosby Elsevier; 2008
• Dakin MC, Leppard B, Theaker JM. The palisaded, encapsulated neuroma (solitary circumscribed neuroma). Histopathology. May 1992;20(5):405-410
• Koutlas IG, Scheithauer BW. Palisaded encapsulated ("solitary circumscribed") neuroma of the oral cavity: a review of 55 cases. Head Neck Pathol. Mar 2010;4(1):15-26