Malignant fibrohistiocytoma of the parotid region. Report of a case.

Most salivary gland tumors are benign, malignant lesions accounting for 15-30% of the total. The most frequent site of salivary gland neoplasms is the parotid gland (80% of all cases). We present a case of malignant fibrohistiocytoma with atypical features due to its location (in the parotid region), size and rapid growth. Generally, this type of tumor arises in the lower limbs and in the abdomen. When located in the parotid gland, these lesions appear as a firm, slow growing and painless mass. Due to the low frequency of such lesions and their clinical behavior, the imaging study and fine-needle aspiration biopsy findings tend to diagnose them as pleomorphic adenoma. The definitive diagnosis requires microscopic study of the resection piece using immunohistochemical techniques. The treatment of choice is surgery, occasionally associated to radiotherapy. The success of treatment is dependent upon complete resection of the tumor - long term follow-up being necessary due to the risk of recurrence or distant metastasis.