Massive infra-clinic invasion of the facial nerve by a myoepithelial carcinoma of the parotid.

We report a new case of myoepithelial carcinoma of the parotid gland in an 8-year-old girl. This is the first case published in a child. The parotid tumour was slightly tender and measured almost 2 cm in diameter. There was no associated facial nerve paralysis despite surgical and histologic evidence of massive facial nerve infiltration. We performed total parotidectomy with resection of the intra-mastoid portion of the facial nerve completed with prophylactic lymph node dissection. Eight months after surgery, MRI revealed a deep-lying recurrence, which required reintervention. There has been no subsequent recurrence 18 months after surgery. Microscopic examination of operative specimens confirmed the diagnosis of parotid myoepithelial carcinoma with fusiform cells. Immunohistochemical markers were positive for cytokeratin, epithelial membrane antigen, smooth muscle actin, S-100 protein, anti-desmine and anti-vimentine. This difficult to diagnose tumour, which was individualised by the World Health Organisation in 1991, is considered a moderate to high-grade malignancy when it develops in a pleomorphic adenoma or appears de novo.