Solitary circumscribed neuroma

Last revised by Tom Foster on 28 Jul 2023

Solitary circumscribed neuromas, also known as palisaded encapsulated neuromas,  are benign tumors primarily occurring in the cutaneous tissues of the face, often at the mucocutaneous border 1

Although they can occur at any age, there is a predilection for later middle age (40-60 years) 1

Typically solitary circumscribed neuromas present as small (<1 cm) cutaneous nodules, usually affecting the face (90%), often adjacent to the lips or on the nose or forehead. They are rounded firm and painless and almost always solitary 1.

The diagnosis of solitary circumscribed neuromas is a pathological one 1. Diagnostic criteria according to the WHO classification of soft tissue and bone tumors (5thedition) 1:

  • circumscribed cutaneous Schwann cell-rich nerve fiber proliferation

  • diffuse S100 positivity and focal NFP staining

  • possible incomplete peripheral capsule with positive perineural markers (e.g. EMA, Glut-1)

Solitary circumscribed neuromas are composed of Schwann cells and to a lesser degree axons. 

These tumors are usually spherical or ovoid, and usually solitary although occasionally a cluster of nodules is present 2. The cut surface of these tumors is pale grey and firm in texture 1

Solitary circumscribed neuromas are composed of bland spindle-shaped cells organized in fascicles. The cells have wavy nuclei that sometimes arrange themselves in parallel lines, reminiscent of palisading (thus the earlier term palisaded encapsulated neuroma) and are embedded in a background of hyalinized collagen below an intact epidermis 1,2. Involvement of the superficial subcutis is sometimes encountered 1,2.

A thin fibrous capsule is sometimes present. No anaplasia or atypia 1

  • S100: positive

  • NFP: positive in small nerve fibers within the tumor

  • EMA: positive in the capsule but not in the tumor 

  • claudin-1: positive in the capsule

  • GLUT-1: positive in the capsule

As these are small and purely cutaneous lesions, they rarely if ever require imaging. 

Solitary circumscribed neuromas are benign with no potential for local invasion or metastasis. Treatment with excision is for cosmetic purposes. 

Solitary circumscribed neuromas were first described in 1972 using the name palisaded, encapsulated neuroma 3.

Other cutaneous nodules, including: 

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