• Harmatomatous proliferations of nerve sheath components
    • Divided into spontaneous (palisaded encapsulated neuroma) and traumatic types

    Palisaded encapsulated neuroma:

    Clinical Features:

    • Adults
    • Most occur on the face.
    • Small skin-colored, dome-shaped papules

    Histologic Features:

    • Well-circumscribed dermal nodule
    • Tight fascicles of spindle cells with ovoid or wavy nuclei
    • The fascicles are often separated by clear clefts.
    • Partially enclosed by a thin capsule composed of perineurium
    • Significant palisading is usually not present, despite the name.
    • Multiple tumors with an identical appearance, with the exception of encapsulation, can be seen in multiple mucosal neuroma syndrome or MEN 2A.
    • S-100 positive
    • The perineurial capsule is positive for EMA.

    Traumatic neuroma:

    Clincial Features:

    • Occurs following damage to a peripheral nerve, with Wallerian degeneration and subsequent imperfect regeneration, resulting in an irregular, disorganized growth at the proximal end of the transected nerve.
    • Firm, skin-colored papule or nodule at a site of previous trauma
    • Older lesions may be painful.
    • Supernumerary digits represent a form of traumatic neuroma occurring after in utero amputation of an extra digit.

    Histologic Features:

    • Well-circumscribed dermal or subcutaneous nodule
    • Haphazard tangle of nerve fascicles varying in size and shape, separated by collagen and variable chronic inflammation
    • The nerve fascicles closely recapitulate normal nerve tissue, with normal proportions of the various cell types.
    • The lesion is partially or completely enclosed in a fibrous sheath.
    • Mucinous changes may be seen in early lesions.
    • S-100 positive
    • The perineurial cells within the fascicles are positive for EMA.

    Cases associated with this book:

  • Neuroma
    Author: Stephen Lyle, M.D., Ph.D.

    Conference: Dr. Z's Consultations