Juvenile Fibrosarcoma of the Parotid Gland in an Adult Patient: A Case Report.

Salivary gland sarcomas are rare neoplasms, with the parotid gland being the most frequent site of involvement. Among these, fibrosarcoma represents an exceptional variant. Its diagnosis is primarily through histopathological and immunohistochemical analysis. Its presentation in the parotid gland is rare, and the occurrence of the infantile-juvenile subtype in an adult patient has not been previously described. In this clinical setting, we report the case of a 29-year-old man presenting with a rapidly growing right preauricular mass and ipsilateral facial paresis. Computed tomography revealed a solid lesion involving the superficial and deep lobes of the parotid gland, extending into adjacent spaces with facial nerve involvement, without distant metastasis. Total parotidectomy with selective neck dissection was performed. Histopathological examination demonstrated a spindle-cell neoplasm with perineural invasion. Immunohistochemistry was negative for epithelial, neural, and muscular markers, with focal smooth muscle actin positivity and a low proliferative index (Ki-67: 4%), consistent with juvenile fibrosarcoma. The case was evaluated by a multidisciplinary team, and after complete surgical resection with negative margins, adjuvant radiotherapy was recommended due to the high risk of local recurrence.