Dermatology Online Journal

Perineurioma - Two cases (Abstract)
Robert Baran, MD and Christophe Perrin, MD
Dermatology Online Journal 8(2): 22A

Nail Disease Center and Dept Histopathol, Hopital Pasteur, Nice, FRANCE

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Neurogenic tumours of peripheral nerves involving the terminal phalanx are very rare. Among these tumours, neuroma, neurofibroma, schwannoma granular cell tumour and so-called rudimentary supernumerary digits are the best known. We have had the privilege to observe a patient with a neurogenic tumour of the nail apparatus not described hitherto in this location, the perineurioma (PNA). During the last years a number of new entities of neural tumors has been described and advances in immunohistochemistry and electron microscopy have helped us better to understand the cytological differentiation of these neoplasms.

We report two cases of subungual perineurioma presenting as a monodactylous clubbing for one of them. A red, pea-size tumor, round and well-demarcated, involving hyponychium and distal groove was the presentation of the second case.

Were it not for the absence of pain, our first clinical diagnosis would have been osteoid osteoma. In addition, it was impossible to rule out subungual neurofibroma, giant cell tumor, lipoma, or even myxoid pseudocyst in a subungual location. Thus immunohistochemical findings indicate that benign peripheral nerve sheath tumors should be placed in at least three categories: schwannoma, neurofibroma and perineurioma. In the latter, the cells demonstrate a strong diffuse staining for vimentin and EMA and negativity for S 100 protein.Surgical removal is the best treatment of this benign tumor, but recurrences are not exceptional.

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