Epithelial Sheath Neuroma: A New Entity

Abstract

The authors describe four examples of a peculiar cutaneous lesion characterized histopathologically by a proliferation of enlarged nerve fibers ensheathed by squamous epithelium involving the superficial dermis. The perineural epithelial sheaths were composed of uniform squamous epithelium with evidence of cornification in the form of dyskeratotic cells or resulting in orthokeratotic basket-weave corneocytes. Immunohistochemical studies confirmed the epithelial and neural nature of the two components of the lesions, with the nerve fibers expressing immunoreactivity for S-100 protein, neurofilaments, CD57, and nerve growth factor receptor, whereas the perineural epithelial sheaths showed immunoreactivity for cytokeratins. The authors propose the term "epithelial sheath neuroma" for this lesion and believe that it is a distinct and a previously undescribed benign neoplasm of both cutaneous nerves and epithelial elements.

Reactive Neuroepithelial Aggregates of the Skin

“…Ackerman [10], in 1957, first described breast ducts within a nerve in a biopsy specimen from a patient without other evidence of carcinoma. Subsequently, such perineural involvement by nonneoplastic epithelium has been reported not only in the breast [ 1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14] but also in prostate [ 1 5 ], pancreas [ 1 6-1 8], vas deferens [19], gallbladder [20,21] and endometriosis [22].…”

Reparative Perineural Hyperplasia: A Series of 10 Cases

“…7 Microscopically, the perineural space is occupied by a cellular concentric epithelial proliferation showing squamous differentiation and no atypia. Table 2 compares the features expected in conditions that should be included in the differential diagnosis of reparative perineural hyperplasia (Table 2).…”

Reexcision Perineural Invasion: A Mimic of Malignancy

“…This rare condition has only been reported in a single series of 4 cases. 8 The lesion usually occurs on the back of elderly females and is said to be characteristic, with nerve hypertrophy and a perineural proliferation of blandappearing squamous epithelial cells. The reported cases have not shown associated scarring or reparative reaction as seen in reexcision perineural invasion.…”