Surgical Pathology Criteria

Solitary Circumscribed Neuroma

Differential Diagnosis

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

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