[Significant factors affecting the operation time for benign parotid tumor].

Tumors of the parotid gland are fairly frequent among head and neck tumors. Parotidectomy for benign tumors is necessary for diagnosis and therapy. Furthermore, acquiring the skill for this operation is a significant step in the training course of an otolaryngologist Thus, it is useful to analyze the operation time and determine the factors affecting it to evaluate the progress in the operation skill. To measure the operation time and determine the factors affecting it, 71 cases, including 43 cases of pleomorphic adenomas and 28 cases Warthin's tumor, were retrospectively reviewed to the determine if the operation time depended on the age, sex, operated side, presence of complications, BMI, bleeding volume, tumor size, tumor location, exposure of branches of the facial nerve, and experience of the surgeon. Multivariate analysis was used to determine the factors correlated with the operation time. The results revealed that the bleeding volume, tumor size, tumor location and experience of the surgeon were significantly correlated with the operation time, whereas age, sex, operated side, presentation of complications and BMI showed no correlation with the operation time. Furthermore, surgeons with the experience of operating 20-39 cases took almost the same time for the operation as the surgeon with the experience of operating more than 40 cases. Taken together, to shorten the operation time, the inexperienced surgeon should start with smaller tumors and surgery in the superficial lobe in the initial training period, and supervision by well-experienced supervised surgeons is required until 30-40 are undertaken.

Lipoma in the deep lobe of the parotid gland: a case report.

We report here on a rare case of lipoma in the deep lobe of the parotid gland. MRI revealed that the tumour was situated mainly in the deep lobe and it extended posteriorly and medially into the space between the sternocleidomastoid muscle and the posterior belly of the digastric muscle, with slight extension into the parapharyngeal space. This tumour produced strong signals on T1- and T2-weighted MR images and weak signals on fat suppression images. In addition, MRI clearly showed the margin of the tumour, which enabled us to readily distinguish the tumour from the surrounding adipose tissue. The images suggested a diagnosis of deep lobe parotid lipoma with posteromedial extension to the sternocleidomastoid muscle, which proved true at surgery. We thus believe that MRI is highly useful, perhaps even necessary, in diagnosing tumours of the head and neck.