Myxoid neurofibroma in a child. An asymptomatic nodule on the finger

ARTICLE

ejd.2010.1239

Auteur(s) : Annalisa PATRIZI¹, Matelda MEDRI^1,2, Fabíola AFFOLTER ORLOWSKI³, Cosimo MISCIALI¹, Carlotta BARALDI¹, Iria NERI¹ mateldamedri@libero.it

¹ Dermatology. Department of Internal Medicine, Geriatrics and Nefrologic Diseases, University of Bologna, via Massarenti 1, CAP 40128, Bologna, Italy

² Istituto Tumori Romagna, IRST, Meldola/Forlì, Italy

³ Pontificia Universidade Católica do Paraná, Italy

Myxoid neurofibroma is a benign tumor of perineural cell origin [1, 2]. Myxoid neurofibromas are usually solitary lesions, occurring in adults, on the extremities. We report an unusual case of a digital myxoid neurofibroma in a child.

A 6-year-old girl presented with an asymptomatic dome-shaped nodule 3 mm in diameter on her right index finger (figure 1A). The surface was smooth and glistening. On palpation the lesion showed hard consistency and remained asymptomatic. The lesion had developed about 1 year earlier and had gradually enlarged. The parents and patient denied trauma or chronic irritation at the site of the lesion. Physical examination of the patient did not reveal any other cutaneous lesion. Family history was unremarkable; her mother and her sister have two café-au-lait spots each. Echography showed a hypoechogenic mucoid nodule of the dermis, 2.8 × 2.9 mm in diameter. Excision of the tumor was performed under digital block without complication and a sample submitted for histological evaluation.

Histopathology revealed a well-circumscribed nodule within the dermis, characterized by cells with small, thin, oval, wavy nuclei, in a stroma of delicate fibrillary collagen bundles with mucin and rudimentary nerve fascicles (figures 1B, C). Alcian blue and S-100 (figure 1D) immune stainings were positive. Myelinbasic protein and EMA immune stains were negative. Rare mast cells were detected in the mucinous stroma. The evaluation combining clinical and microscopic findings allowed a diagnosis of myxoid neurofibroma. There was no recurrence after a 6-month-follow-up.

In our patient myxoid neurofibroma was a solitary lesion unrelated to Von Recklinghausen's disease or to NAME syndrome.

Myxoid neurofibroma is a benign tumour of perineural cell origin and is usually a solitary lesion. Myxoid neurofibromas have a higher incidence in teenagers and young adults [3] and may be found at any site on the body surface [4]. They can, rarely, be observed on the fingers in a peri- or subungual location [1, 5]. Myxoid neurofibromas are well-circumscribed, although unencapsulated, and are composed of S100 protein positive spindle cells with wavy nuclei and indistinct cytoplasm, associated with wire-like collagen fibrils. Mast cells are usually easily found. The presence of axons and intralesional nerve bundles allows distinction from schwannoma and myxoid neurothekeoma. Myxoid neurofibroma should be histologically differentiated from solitary cutaneous myxoma neurothekeoma, characterized by a multi-lobulated dermal lesion consisting of loosely arranged spindle and stellate cells within abundant stromal mucin, and ossifying and non-ossifying fibromyxoid tumors, made up of cords and nests of polygonal cells with eosinophilic cytoplasm and small, round, vesicular nuclei [6]. The neoplasm is most notorious for being a component of the NAME syndrome (nevi, atrial, myxoma, myxoid neurofibroma and ephelides). All these lesions are reported in adulthood. The most appropriate therapy for solitary myxoid neurofibroma is complete surgical resection. To the best of our knowledge this is the first report of a myxoid neurofibroma in a child.

Disclosure

Financial support: none. Conflict of interest: none.

References

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