Cellular neurothekoma of the nasal dorsum

ARTICLE

Auteur(s) : Mireia Yébenes Marsal¹, Òscar Escuder², Irgmard Costa³, Artur Díaz-Carandell², Jesús Luelmo¹

¹Departments of Dermatology
²Departments of Maxillofacial Surgery
³Departments of Pathology, Hospital Universitari de Sabadell, C/Parc Taulí s/n, 08208, Barcelona, Spain

Neurothekoma refers to a very uncommon benign tumour, of uncertain origin, although it has been suggested that it might arise from the peripheric nerve sheath. Harkin and Reed first described it in 1969 [1]. Neurothekomas can be divided into three histological subtypes: cellular, mixed and myxoid, according to the quantity of myxoid matrix the tumour contains.

We report a 28-year-old man, with an unremarkable previous medical history, referred to the Dermatology Department because of a slow growing lesion over an 8-month period on the dorsum of the nose (figure 1). On physical examination, an 8 mm papule, red-brownish, completely asymptomatic, and not infiltrating on touch, was observed. Histological investigation showed a fairly well delimited tumoral lesion, localized in the reticular dermis, formed by epithelioid and spindle cells, surrounded by sclerotic collagen. Mitoses were occasionally seen. The immunohistochemical study showed that the tumoral cells expressed D2-40, vimentin, neuronal specific enolase, CD10 and were stained with smooth muscle actin. They were negative to CAM5.2, QAE1/AE3, Q116, EMA, S-100, HMB-45, Melan-A, CD68, CD56, chromogranin, synaptophysin and neurofilaments.

On this pathology the diagnosis of cellular neurothekoma (CN) was made. We proceeded to operate, a simple excision was carried out. Excision was diagnosed as incomplete by the post-op pathology examination. As recurrence is very uncommon, even after incomplete excision, no other procedure was undertaken. Given the young age of the patient and the unusual diagnosis, in spite of it being a benign tumour, routine follow-up was established. At one year post-op, recurrence was observed and after discussion in our multidisciplinary unit (dermatologist, maxillofacial surgeon and pathologist) we decided to perform further surgery aiming for complete excision. The surgery achieved its goal: complete excision; and the pathological study was consistent with the previous one. To date, approximately 2 years after the second surgery, the patient remains well and no recurrence has been observed.

Most CN are localized on the head and neck area and on the upper limbs of young adults, usually during the three first decades, with female predominance. No association with neurofibromatosis has been found. CN usually presents as a solitary, well-defined red-brownish lesion of approximately 1-2 cm in diameter. On histological examination a neatly defined, non-capsulated lesion localized in the dermis and rarely infiltrating the subcutaneous fatty tissue is seen. The tumour is usually composed of lobules with fibrovascular septae between them. These lobules are composed of spindle-shaped cells with eosinophilic cytoplasm and myxoid matrix among the cells. Occasionally, multinucleated giant cells can be found. Although atypical cases of CN have been described, with cellular pleomorphism, subcutaneous fatty tissue infiltration and mitosis, these forms of CN have not shown a more aggressive behaviour [2, 3]. Recurrence rates of all forms of CN, even after incomplete excision, are negligible.

Recently a relationship between plexiform fibro-histiocytic tumour (PFHT) and CN was found, the former being a more aggressive type due to its localization on the trunk and inferior limbs and its higher capacity for infiltration of the subcutaneous fatty tissue [4]. Moreover, ultra-structural studies may aid in discrimination from CN; observation of “zebra body”-like lysosomes in the initial specimen providing ultrastructural evidence seemingly favoring a diagnosis of PFHT [5].

In the immunohistochemical study, tumoral cells are positive for smooth muscle actin, vimentin, neuronal specific enolase and negative for S-100, although positive for a related protein: the S100A6 [6].

Differential diagnosis should include other dermally localized lesions, such as malignant melanoma, Spitz naevus, fibroblastic tumours (dermatofibroma, atypical fibroxantoma) among others. The treatment of choice is complete excision of the lesion.

Acknowledgements

References

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3 Fetsch JF, Laskin WB, Hallman JR, Lupton GP, Miettinen M. Neurothekeoma: an analysis of 178 tumors with detailed immunohistochemical data and long-term patient follow-up information. Am J Surg Pathol 2007; 3: 1103-14.

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5 Wartchow EP, Goin L, Schreiber J, Mierau GW, Terella A, Allen GC. Plexiform fibrohistiocytic tumor: ultrastructural studies may aid in discrimination from cellular neurothekeoma. Ultrastruct Pathol 2009; 33: 286-92.

6 Plaza JA, Torres-Cabala C, Evans H, Diwan AH, Prieto VG. Immunohistochemical expression of S100A6 in cellular neurothekeoma: clinicopathologic and immunohistochemical analysis of 31 cases. Am J Dermatopathol 2009; 31: 419-22.