Carcinoma ex pleomorphic adenoma is a rare malignant parotid neoplasm arising from primary or recurrent benign pleomorphic adenoma. Histologically, it can be sub-classified by upwards of eight different variations (e.g., myoepithelial carcinoma, salivary duct carcinoma, adenoid cystic carcinoma sarcomatoid carcinoma). We present the fourth case in the literature of sarcomatoid carcinoma arising from an underlying pleomorphic adenoma of the parotid gland. We present a case of a 47-year-old female who consulted for a left parotid mass of 15cm long axis. There was no facial paralysis. Fine needle aspiration cytology smears showed a pleomorphic adenoma. The parotid MRI showed a left parotid mass, with heterogeneous signal (hyposignal T1 and hypersignal T2 and in diffusion sequences). The patient underwent a total parotidectomy with a pleomorphic adenoma on extemporaneous examination. Histological examination of the part revealed a pleomorphic adenoma on which a sarcomatoid carcinoma developed. Therefore, a second operation occurred. We performed selective lymph node dissection carrying out the sectors I, II and III followed by radiotherapy. The evolution was favorable. In addition to its rarity, our case joins historical cases by its huge size.