Expanding the clinicopathologic spectrum of palisaded encapsulated neuroma.

Palisaded encapsulated neuroma (PEN; solitary circumscribed neuroma) is a benign, morphologically characteristic cutaneous or mucosal neuroma. Most are solitary lesions on the face, neck or oral mucosa. Histologically, the majority appears as dermal nodules of Schwann cell-rich fascicles, with or without distinctive encapsulation. To further expand on the existing literature regarding this neuroma, we herein describe three PENs with unique clinical and histopathologic features. All occurred on the acral skin, a rarely described site. Furthermore, one exceptional patient presented with multiple PEN on the bilateral hands, biopsies of which showed a prominent plexiform architecture. Awareness that PEN may occur on acral skin, may rarely present as multiple lesions, and recognition of the plexiform variant is important because PEN may histologically mimic other peripheral nerve sheath tumors. Additionally, misdiagnosis may have significant clinical implications.