Reviewer(s): Dharam M. Ramnani, MD
TRAUMATIC NEUROMA: Traumatic neuroma is an exuberant non-neoplastic proliferation of nerve endings in response to trauma or surgery. In a severed or injured nerve, if the proximal and distal stumps are not approximated (or if there is no distal stump), haphazard proliferation of Schwann cells at the proximal stump gives rise to a traumatic neuroma. It can develop following surgery (amputations, cholecystectomy), trauma, and following autoamputation in utero of supernumerary digits. Some cases are associated with arteriovenous aneurysms, human bite, and deep burns. PALISADED ENCAPSULATED NEUROMA: It presents as an asymptomatic solitary papule on the face and within oral cavity of middle-aged and older adults. Distal extremities, eyelids and penis may be rarely involved. There is no association with NF-1 or MEN 2B. It appears as a circumscribed dermal or subcutaneous nodule composed of short intersecting fascicles of Schwann cells. It is S-100 positive and GFAP negative. Neurofilament stains numerous axons within the lesion. PACINIAN NEUROMA: It is a localized hyperplasia of pacinian corpuscles. It usually follows trauma and presents as a localized painful mass on the digits. Microscopically, it shows an increase in the size and number of pacinian corpuscles. Reference: Enzinger & Weiss's Soft Tissue Tumors, Sixth Edition, 2014; p. 786-790.