Skin, palisaded encapsulated neuroma

The palisaded encapsulated neuroma (PEN, also known as solitary circumscribed neuroma) is a subtype of neuroma; a benign proliferation of peripheral nerve fibers in which the ratio of axons to Schwann cell fascicles approach 1:1. PEN typically presents as a solitary nodule on the face of middle aged individuals. It is a circumscribed dermal tumour composed of well-developed fascicles of Schwann cells and axons. Often, a thin perineural connective tissue capsule surrounds the tumour (as seen in this case).