PALISADED AND ENCAPSULATED NEUROMA
This tumor was described by Richard J. Reed et al about 27 years ago, but it is not widely known. These are not rare, and they may be mistaken for leiomyomas and neurofibromas. They usually occur on the face. Packed fascicles composed of monotonous spindle cells form an expasile unit that is sharply demarcated from the surrounding stroma. Special stains demonstrate numerous axons (about a one to one ratio) within the masses of wavy Schwann cells, but such stains are usually not  necessary in most cases. Branches of the involved nerve may also be involved and can give the tumor a plexiform appearance. These neuromas are spontaneous (not related to known trauma), and they are not associated with neural or endocrine abnormalities.
Scan of a papule from the face.
Low power of same. Note sharp line of demarcation between papule and dermis.
High power of same.
Very high power of spindle cells cut in cross-section. Arrows point to cross-sections of a few of the many structures resembling tiny tubules. These can be mistaken for the clear zones found in smooth muscle.

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