This work was done in: Department of ENT and Head and Neck Surgery, Ganesh Man Singh Memorial Academy of ENT and Head and Neck Studies, TU Teaching Hospital, Kathmandu, Nepal.

Introduction

Lipoma is a most common benign soft tissue neoplasm in human being. It occurs predominantly in upper back, shoulder and abdomen. ₁ Lipoma of head and neck region is involved in 15 to 20% of cases. The incidence of lipoma in parotid tumours is 1 %. ₂

They are seldom considered in the initial differential diagnosis of parotid mass and mistaken for other parotid neoplasm. Very few cases in literature have been reported about Parotid lipoma and none from Nepal.

Case Report

A 53 year old woman presented in department of ENT and Head neck surgery, T.U. Teaching Hospital, Kathmandu with complain of painless, slow growing swelling in the left parotid region. Clinical examination revealed a single, soft, non-tender well defined and freely mobile swelling of 5x4 cm size in the left parotid region, elevating the left ear lobule. There was no history of trauma, infection other swelling in the neck region. Facial nerve was intact. Fine needle aspiration cytology (FNAC) of the swelling revealed benign lipomatous lesion of the parotid gland. The patient underwent left near total conservative parotidectomy. Per operative findings showed a 8x6cm, multi-lobulated yellowish mass arising from deep lobe of the left parotid gland (Fig:1).

Figure 1

Figure 1: Showing Parotid Lipoma after surgery

Histology revealed matured adipose tissue with thin capsule and adjacent salivary gland shows lipomatous infiltration. Thus, final diagnosis made was lipoma of the deep lobe of the left parotid gland.

Discussion

Lipoma of the parotid gland is rare finding and seldom considered in the differential of parotid swelling. Lipoma of the superficial lobe of parotid gland is frequently reported, but from the deep, lobe it is extremely rare and only few of them are reported in world literature. In our case, the lipoma was arising from the deep lobe of parotid gland. There are benign tumours which histologically are similar to mature adipose tissue, but the presence of a fibrous capsule serves to distinguish them from simple aggregation of fat. Clinical diagnosis of a parotid lipoma is usually difficult. They appear as a slow growing, non-tender, mobile and well-differentiated soft mass.

FNAC, Computerized tomography (CT) scan and Magnetic resonance imaging (MRI) are the modality of diagnosis and extent of surgical lesion before surgical exploration. ₃ MRI is the investigation of choice mentioned by most of the authors, but CT scan has also high accuracy rate. It shows homogenous mass with few septations and has less water density. But the differentiation between intraparotid and extraparotid masses is best made by MRI. ₄ Lipomas produce strong signals on T1 and T2 weighted MR images and weak signals on fat suppressed images. FNAC commonly performed in the diagnostic work-up for parotid mass, does not provide sufficient data for diagnosis.

The surgical management of lipoma in the parotid is controversial. Most authors suggest a formal superficial parotidectomy with full exposure of the facial nerve and its branches for deep parotid lobe lipoma. ₅ Enucleation of excision of the well-encapsulated tumour with a rim of parotid gland tissue is another surgical approach. In our case near total conservative parotidectomy was done. Recurrence rate of parotid lipoma is very low- 5% in all lipoma cases as it is usually well-encapsulated. ₆