Palisaded Encapsulated Neuroma
Palisaded encapsulated neuroma (solitary circumscribed neuroma) is a common asymptomatic lesion that presents as a solitary papule on the face (nose, nasolabial folds, cheeks) 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.
Microscopically, it appears as a circumscribed dermal or subcutaneous nodule but it may show multinodular or plexiform growth pattern. It is composed of Schwann cells with wavy hyperchromatic nuclei, arranged in short intersecting fascicles. Nuclear palisading is uncommon. Rare cases show degenerative-type nuclear atypia or epithelioid morphology. Overlying epidermis may be mildly hyperplastic. The lesion is S-100 positive (shown here) and GFAP negative. Neurofilament stains numerous axons within the lesion. It is cured by simple excision.
Image courtesy of: Ed Uthman, MD, Houston, Texas.