Abstract

Neurofibroma Transformation to Malignant Peripheral Nerve Sheath Tumor in the Parapharyngeal Space: A Case Report

Author(s):Razan A. AlDhahri, Rana A. AlJunidel, Nasser A. Benomran, Hussain M. Alkaff, Nouf M. Aloraini, Raghad A. Alotaibi, Joon Seon Song, Turki M. Almuhaimid and Soon Yuhl Nam

The incidence of sporadic malignant peripheral nerve sheath tumors (MPNSTs) in general population is as low as 0.001%. Whereas in association with neurofibromatosis type 1 (NF1), the lifetime risk of MPNSTs is estimated to be 8-13%. MPNSTs are potentially found on the trunk and extremities. They are infrequently observed in the head and neck. Thus, they are extremely rare to arise from the para-pharyngeal space. Consequently, to the best of our knowledge, benign neurofibroma malignant transformation has never been reported in the para-pharyngeal space yet. Therefore, in this article, we report the first case of neurofibroma transformation into MPNST in the parapharyngeal space of an NF1 patient. The cornerstone treatment is complete surgical excision of the tumor. In most cases, it is not possible to obtain clear margins in the head and neck region because of the lack of circumscription and anatomical complexity of the area. Recurrence rate ranges from 40% to 68%, whereas 5-year survival was reported ranging from 16% to 52%. Poor prognosis is linked with tumor size exceeding 5 cm, association with NF1, old age, distant metastases, inability to achieve tumor-free margins, high tumor grade, and poor differentiation. In conclusion, due to the rarity of this disease, only a few large studies investigated recurrence rate and survival. Poor outcomes are attributed to the rarity of the disease and complexity of the region. More cases shall be reported to improve our knowledge about the incidence, course, and prognosis of the disease, and allow for new effective management techniques discovery.

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