Traumatic neuromas develop from a nonneoplastic proliferation of the severed, partially transected, or injured nerve as a result of trauma (lacerating or penetrating) or surgery (specially limb amputation).

Clinical presentation: Presents as a firm nodule that may be tender or painful.  

Site: The most common location for traumatic neuromas is the lower extremity after amputation, followed by the head and neck (frequently in the oral cavity, because more than 50% of these lesions are related to tooth extraction). Other sites include the radial nerve and brachial plexus .

Traumatic neuromas have been divided into two major categories: (i) Spindle neuromas are internal, focal, fusiform swellings secondary to chronic friction or irritation to a nondisrupted, injured but intact nerve trunk. (ii) Lateral or terminal neuromas are the result of severe trauma with disruption or total transection of a nerve .

Gross: These lesions are circumscribed white gray nodules located in continuity with the with proximal end of the injured or transected nerve. Traumatic neuromas arise 1–12 months after transection or injury, and vary in size with no malignant potential .

Microscopic features: (ESCOP)Image Links1   2   3   4

Traumatic neuromas are nonneoplastic , nonencapsulated, poorly circumscribed lesions and is characterized by disorderly outgrowth of all normal components of a nerve fascicle. The components include tangled masses of axons, Schwann cells, endoneurial cells, and perineurial cells in a dense collagenous matrix with surrounding fibroblasts. The participation of all elements of the nerve fascicles distinguishes this lesion from the neurofibroma.

D/D:  Palisaded encapsulated neuroma(PEN): Immunostaining with EMA reveals that in traumatic neuroma the individual fascicles are usually surrounded by perineurial cells, whereas in PEN the perineurial cells are observed mainly in the capsular areas and only rarely within the fascicles. Traumatic neuroma contains considerably larger amounts of collagen (types I and III), acidic mucin, and myelin products.

Abstract:

 A light microscopical study on the structure of traumatic neuromas of the human lingual nerve.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005 ; 99(4):395-403.

Granular Cell Traumatic Neuroma.Archives of Pathology and Laboratory Medicine: Vol. 124, No. 5, pp. 709–711

Comparative light-microscopic and immunohistochemical study of traumatic and palisaded encapsulated neuromas of the skin.AmJDermatopathol.1992;14(6):504-10

Aberrant expression of macrophage-associated antigens (CD68 and Ki-M1P) by Schwann cells in reactive and neoplastic neural tissue. Light- and electron-microscopic findings.Mod Pathol. 1993 Jul;6(4):463-8.

Traumatic Neuroma after Neck Dissection: CT Characteristics in Four Cases. AJNR Am J Neuroradiol. 2000 Oct;21(9):1676-80(full text)

This non-neoplastic lesion was described by Thomas Morton in 1876.

Cause: It commonly occurs in female adults and is probably related to nerve compression against the intermetatarsal ligament from foot position in high-heeled shoes or due to ischaemia.

Clinical presentation: Patient complains of severe pain in the sole of the foot, in the region of the metatarsal heads or metatarsophalangeal joints.

Site: There is perineural fibrosis of the plantar digital nerve. The nerve is usually affected at the level of the metatarsal head and is common between the third and fourth metatarsals and then between the second and third.

Gross: There is thickening or fusiform swelling of the plantar digital nerve at its bifurcation, with thickening of adjacent tendosynovial tissues. GROSS IMAGE

Microscopic features: There is prominent endoneurial, perineurial and epineurial fibrosis and hyalinization associated with loss of axons. There is fibrosis within adipose tissue.
Adjacent blood vessels show fibrosis and thickening of the walls. There may be fibrointimal thickening with occlusion of small blood vessels.

Abstract:

Histological comparison of the third interdigital nerve in patients with Morton's metatarsalgia and control patients.Aust N Z J Surg. 1994 Jun;64(6):421-4

Morton's intermetatarsal neuroma: morphology and histological substrate.Foot Ankle Int. 2000 Jul;21(7):558-62

Morton's metatarsalgia: sonographic findings and correlated histopathology.Foot Ankle Int. 1999 Mar;20(3):153-61.

Morton's interdigital neuroma: a clinical review of its etiology, treatment, and results.J Foot Ankle Surg. 1996 Mar-Apr;35(2):112-9; discussion 187-8

Rare lesion characterized by small extremely painful nodule on the fingers of middle-aged adults. These lesions usually occur following trauma. No recurrence is observed after surgical excision.

Microscopic features:  These are uncapsulated lesions composed of abnormal aggregates of morphologically mature Pacinian corpuscles and intervening small nerves set in a fibrous backround.   MICROSCOPIC IMAGE

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Rarely ganglions occur within nerve sheaths (intraneural location).

Cause: This lesion represents a degenerative process rather than a neoplasm.

Site: These lesions involve the large nerves about the knee(popliteal, peroneal,or tibial) at the level of fibular head.  GROSS IMAGE LINK

Clinical presentation: Patients present with a palpable mass or neurologic symptoms resulting from nerve compression

Microscopic features: These lesions show myxoid change surrounded by a fibrous lining and often occur in the connective tissue between the nerve sheath and the nerve, which often results in displacement of the adjacent nerve.