T1 pre-gad T1 post-gad with fat sat T1 post-gad with fat sat

Diagnosis: Acinic cell carcinoma

Acinic cell carcinoma is a malignant primary neoplasm of the salivary glands composed of serous cells. About 50% of patients will have local recurrence and another 20% will have metastases after treatment. Patients may present with a slowly growing parotid mass with variable involvement of the facial nerve. On imaging, there is nothing specific about acinic cell carcinoma when compared to other malignant parotid neoplasms all of which may show enhancement and infiltration into the surrounding structures versus benign tumors which tend to not infiltrate. Inflammatory lesions may however show surrounding infiltration. In this particular case, the lesion has a somewhat misleading, well-circumscribed encapsulated appearance. Other entities to consider in the differential of a solid enhancing parotid mass include adenoid cystic carcinoma, mucoepidermoid carcinoma in the primary malignant category and pleomorphic adenoma or benign mixed tumor and Warthin's tumor in the benign primary category. Due to the presence of lymph nodes within in the parotid gland, nodal metastasis should also be considered; however a nodal mass of this size would probably have some necrosis. Furthermore there is no other abnormal adenopathy seen in these images.

The parotid gland is divided into the superficial and deep lobes by the course of the facial nerve which passes through the parotid superficial to the retromandibular vein. The distinction is important since superficial lesions may be removed by superficial parotidectomy while deep lesions require total parotidectomy. The parotid space is surrounded by the deep cervical fascia which splits and surrounds the parotid space. Contents of the parotid space include in the parotid gland, the external carotid artery, retromandibular vein, the facial nerve, and lymph nodes. A lesion may be identified as being primarily within the parotid space by identifying its epicenter there and by medial displacement of the parapharyngeal space which is adjacent. Related Cases

Lewis Je, Olsen KD, Weiland LH. Acinic cell carcinoma. Cliniopatholigc review. Cancer, Jan 1991; 67(1):p172-9.

Joe VQ, Westesson PL. Tumors of the parotid gland: MR imaging characteristics of various histologic types. AJR, Aug 1994; 163(2):p433-8.

Fulbright R, Panush D, Sze G, et al. MR of the head and neck: comparison of fast spin-echo and conventional spin-echo sequences. AJNR, Apr 1994; 15(4):p767-73.

Freling NJ, Molenaar WM, Vermey A, et al. Malignant parotid tumors: clinical use of MR imaging and histologic correlation. Dec 1992; 185(3):p691-6.















































Warthins tumor Pleomorphic adenoma Acinic cell carcinoma