Management of Lipomas Arising From Deep Lobe of The Parotid Gland Cagatay Han ULKU, Yavuz UYAR Selcuk University, School of Medicine, Department of Otolaryngology Head and Neck Surgery, Konya-TURKEY Subjects and Methods Five patients with lipoma arising from the deep lobe of the parotid gland diagnosed and treated at our clinic between March 1992 and March 2004 were included in this study. Limits of the tumors were determined by CT, and/or MRI. Preoperative FNAB was also performed. Through a classic parotidectomy incision, the parotid gland was exposed. Full exposure of the facial nerve and its branches were performed. The removel of deep lobe parotid lipomas were achieved by enucleation in all cases. Postoperative complication / morbidity, and recurrence were evaluated. Introduction Lipomas are one of the most frequently encountered benign tumors 1 . They usually occur in the immediate subcutaneous tissue in the head and neck region. Lipomas originating in the deep parotid lobe are extremely rare, and only five cases have been reported in the English literature 2-5 . The removal of deep lobe parotid lipomas requires full exposure of the facial nerve 6 . Results One case was female and 4 cases were male. The mean age of the group was 46.2 years. The most common symptom was an otherwise asymptomatic mass on the parotid region and/or upper lateral neck. One of 5 patients presented with medial displacement of the lateral pharyngeal wall, and tonsil as the additional physical finding. Examination of preoperative diagnostic test results revealed that CT and/or MR scans accurately verified 100 % of the tumors in relation to the deep lobe of the parotid gland (Figure 1a, 1b). FNAB did not enable us to make a preoperative diagnosis of lipoma in 4 of the cases. In two of the cases, lipomas were partly seated on the superficial lobe, but mainly on the deep lobe of the parotid gland (Figure 2a, 2b). Total excision of the tumor was achieved in all cases (Figure 2c). There was no recurrence of the tumors after a mean follow-up of 60 months. Lipomas produce strong signals on T1 and T2 - weighted MR images and weak signals on fat- suppressed images 5 . Assesment of the exact extention of the tumor is an important consideration for selection of the surgical approach. If the tumor arises from deep parotid lobe, transparotid approach that requires determination the facial nerve branches is appropriate. Otherwise, transcervical approach provides good and safe exposure for excision of the poststyloid extraparotid tumors 2,6,12 . Nevertheless, if the tumor is located in both parotid lobes, it is difficult to precisely determine by the radiodiagnostic modalities, including MRI whether the lipoma has originated from the superficial or deep parotid lobe, as we observed in two of the five cases examined. Layfield et al. reported that FNAB did not contribute to a correct preoperative diagnosis in four of nine benign lipomatous tumors of the parotid gland 13 . There are similary reports in others studies in the literature 5,10 . Similarly, FNAB did not enable us to make a preoperative diagnosis of lipoma in 4 of the cases. Therefore, we pointed out that FNAB has proved to be unreliable in lipomas of the parotid gland. The surgical management of lipomas in the parotid gland is controversial. Most authors suggest a formal superficial parotidectomy with full exposure of the facial nerve and its branches for deep parotid lobe lipomas 2,6,14 . Enucleation or excision of the well-encapsulated tumor with a rim of parotid gland tissue is another surgical approach, and advocated for paraparotid or intraparotid lipomas 2,3,10 . As most of them are well encapsulated, the recurrence rate is as low as 5 % in all lipoma cases 7 . In this study, after full exposure of the facial nerve and its branches were performed, total excision of the tumor by enucleation was achieved with carefully dissection. During surgery, we observed that in two of 5 cases, lipoma was partly seated on the superficial lobe, but mainly on the deep lobe of the parotid gland. After lipoma was resected, the capsule of the superficial parotid gland was re- closed. Neither paralysis nor infections was observed as a complication. There was no recurrence of the tumors after a mean follow-up of 60 months in our cases. References 1. Atsunobu T. Lipoma in the peri-tonsillar space J Laryngol Otol 1994;108:693-5. 2. Janecka IP, Conley J, Perzin KH, Pitman G. Lipomas presenting as parotid tumors. Laryngoscope 1977;87:1007-10. 3. Weiner GM, Pahor AL. Deep lobe parotid lipoma:a case report. J Laryngol Otol 1995;109:772-3. 4. Sueda N, Takeshita M, Chijiwa H, Hara T, Hirakawa N, Iwamura N, et. al. A case of lipoma in the deep lobe of the parotid gland. Otologia Fukuoka 1999;45:211-4. 5. Kimura Y, Ishikawa N, Goutsu K, Kitamura K, Kishimoto S. Lipoma in the deep lobe of the parotid gland: a case report. Auris Nasus Larynx 2002;29:391-3. 6. Maran AGD, Mackenzie IJ, Murray JAM. The parapharyngeal space. J Laryngol Otol 1984;98:371-80. 7. Enzinger FM, Weiss SW. Benign lipomatous tumours, 3rd Edition, St. Louis, Missouri, Mosby; 1995. p.381-430. 8. Barnes L. Tumours and tumour like lesions in head and neck. In: Surgical Pathology of Head and Neck. Vol.1 New York, Marcel Dekker Inc; 1985. p. 747-58. 9. Walts AE, Perzik SL. Lipomatous lesions of the parotid area. Arch Otolaryngol 1976;102:230-2. 10. Srinivasan V, Ganesan S, Premachandra J. Lipoma of the parotid gland presenting with facial palsy. J Laryngol Otol 1996;110:93-5. 11. Som PM, Braun IF, Shapiro MD, Reede DL, Curtin HD, Zimmerman RA. Tumors of the parapharyngeal space and upper neck: MR imaging characteristics. Radiology 1987;164:823-9. 12. Pensak, ML, Gluckman JL, Shumrick KA. Parapharyngeal space tumors:An algorithm for evaluation and management. Laryngoscope 1994;104:1170-3. 13. Layfield LJ, Glasgow BJ, Lufkin R. Lipomatous lesions of the parotid gland: Potential pitfalls in fine needle aspiration biopsy diagnosis. Acta Cytol 1991;35:553-6. 14. Malave DA, Ziccardi VB, Greco R, Patterson GT. Lipoma of the parotid gland: report of a case. J Oral Maxillofac Surg 1994;52:408-11. 15. Mehle ME, Kraus DH, Wood BG, Benninger MS, Eliachar I, Levine HL, et. al. Facial nerve morbidity following parotid surgery for benign disease:The Cleveland Clinic Foundation experience. Laryngoscope 1994;104:1487-94. 16. Yamashita T, Tomoda K, Kumazawa T. The usefulness of partial parotidectomy for benign parotid gland tumors: a retrospective study of 306 cases. Acta Otolaryngol Suppl. (Stockh) 1993;500:113-6. Conclusion Different from the other location, lipomas arising from the parotid gland can not be easily resected by simple dissection. Full exposure of the facial nerve and its branches is essential. Nevertheless, if the surgeon does not have experience for parotid surgery, she/he should not attempt to perform that surgery. Figure 1a. T: Tumor Figure 2a. T: Tumor FN: Facial nerve Figure 2c.. Discussion Lipoma is undeniably one of the most frequently encountered benign mesenchymal tumors. This tumor may originate from adipose tissue in any part of the body 1 . It may be single or multiple and may occur as a superficial or deep-seated tumor 7 . Approximately 13 per cent of lipomas occur in the head and neck region. However, majority of them are found in the subcutaneous tissues 8 . Lipomas are rarely found in the parotid gland. Among parotid tumors, the incidence of lipoma ranges from 0.6 to 4.4 % 9 . Lipomas arising in the deep parotid lobe are extremely rare, and only five cases have been reported in the English literature, so far 2-5 . Because of their rarity, they are not often considered in the differential diagnosis of parotid tumors 3 . Clinical diagnosis of a parotid lipoma is usually difficult 10 . Lipomas are asymptomatic except for cosmetic or obstructive effects. Pain is not a common feature and is dependent upon the amount of pressure produced by the mass on the surrounding tissues 1 . They appear as a slow growing, non-tender, mobile, and well-delineated soft mass 7,9,10 . Tumors located in the deep parotid lobe often become symptomatic only after reaching a large size, and therefore can be endured for long periods of time. The most common symptom was an otherwise asymptomatic mass on the parotid region and/or upper lateral neck in our cases. One of 5 patients was presented with medial displacement of the lateral pharyngeal wall, and tonsil as the additional physical finding. Although high accuracy rates have been reported for the diagnosis of lipomas by CT scan analysis, MRI is recommended as the study of choice in delineating lipomas by most authors, because it is capable of higher resolution in soft tissues. Differentiation between intraparotid and extraparotid masses is best made by MRI 1,11 Figure 1b. T: Tumor Figure 2b. T1: Tumor seated on superficial lobe, T2: Tumor seated on deep lobe, FN: Facial nerve, P: Parotid gland.