Sir,

A 24 year-old man presented with a pedunculated protruding mass of the back evolving for three years. At physical examination, the tumor was polypoid, pedunculated and measured 2,5cm. Grossly, it was myxoïd and contained cystic and hemorrhagic changes at cut surface.

Histological examination revealed a well-circumscribed, unencapsulated tumor, located in the middle and deep dermis. It was composed of dense cellular areas alterning with myxoïde zones. The cellular areas were formed by long bundles of spindle-shaped cells, with their nuclei arranged back to back in a parallel pattern (Figs 1 and 2). Vessels were numerous and their walls were thick and hyalinized. Immunohistochemically, the tumor cells stained strongly and diffusely for S100 protein (Fig. 3).

The diagnosis of a pedunculated cutaneous schwannoma.

The patient’s informed consent was obtained.

Prior to the study, patient gave written consent to the examination and biopsy after having been informed about the procedure.

DISCUSSION

Schwannoma (also known as neurilemmoma or neurinoma) is a benign nerve sheath tumor which arises from Schwann cells, thus; it can be located anywhere in the body. Cutaneous schwannomas are uncommon [1]. Limbs are their site of predilection [1]. The tumor affects equally the two sexes [2] and is most common in patients aged between 20 and 50 years. Cutaneous schwannomas occur at random without a known cause and are usually solitary. Schwannomatosis is rare and is defined by the presence of multiple diffuse or localized tumors. Some authors considered it as a rare form of neurofibromatosis [3].

Clinically, cutaneous schwannomas grow slowly for several years and are often asymptomatic, but pain, tenderness or paresthesia may occur in up to one third of patients; due to the neural compression by the tumor.

It generally presents as a deep seated nodule located in the deep dermis or in the subcutis. Schwannomas presenting as a pedunculated protruding mass as in our case are exceptional. In our best knowledge, only Seongmin and al reported a similar presentation [4].

Macroscopically, the tumor is encapsulated, gray-white in color, with a smooth, shiny appearance. Cystic changes are sometimes present, particularly in high-sized and deep tumors [4]. In our case, they may be explained by a vascular insufficiency because of the tumor particular form.

The diagnosis of schwannomas is histological. They are well circumscribed, encapsulated by perineurium, and usually located in the deep dermis and the subcutaneous tissue. They are characterized by two types of areas.

Antoni A areas are made of spindle-shaped Schwann cells arranged in interlacing fascicles. The cells have indistinct cytoplasm borders. The nuclei may be aligned in rows or palisades, between which the cytoplasm is fused into eosinophilic material forming Verocay bodies.

Antoni B zones are loosely cellular, myxoïd and edematous. At immunohistochemical study, the tumor cells stain strongly for S 100 protein and are encircled by the type IV collagen [1].

Cutaneous schwannoma must be differentiated histologically from PEN (Palisated and Encapsulated Neuroma) but -in case of pedunculated protruding mass- neurofibroma is the main differential diagnosis because it can present as a pedunculated tumor [1].

Schwannomas treatment is complete surgical removal. In case of incomplete excision, post operative radiotherapy was proposed by some authors [5] but it has not shown its efficacy [2].

By conclusion, in front of a patient with a pedunculated cutaneous mass, schwannoma must be evocated and this unusual clinical feature of this tumor must be included into cutaneous schwannoma‘s appearances to avoid misdiagnosis.

CONSENT

The examination of the patient was conducted according to the Declaration of Helsinki principles. Written informed consent was obtained from the patient for publication of this article.