Patient presents with right facial swelling.
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Lipomas are the most common benign mesenchymal tumors that arise where fat is normally present. These encapsulated tumors are usually subcutaneous and found most commonly in the extremities, trunk, and neck regions. Lipomas in the head and neck are rare, accounting for only approximately 15% with a posterior neck predilection.1 Rarer still are salivary gland lipomas, with the parotid gland having an incidence of only about 4.4% (highest reported). Risk factors include: heredity, obesity, diabetes, radiation, and trauma. These usually occur in the sixth decade of life with a male predilection (5:1).2 These present clinically as a slow-growing, painless mass that becomes symptomatic as the lesion grows. Trauma is the most frequently correlated on clinical history: hematoma formation and lymphatic effusion that leads to fat necrosis and lipoma formation.3 Clinical suspicion is usually low given the rarity of the entity.2
Preoperative imaging is important in characterizing parotid lipomas. On ultrasound, it can have a homogenous, hypoechoic ovoid, or lobulated appearance. On CT, these can be hypodense, homogenous with few septations with Hounsfield units [-50 to -150] which contrasts with the positive density of normal parotid tissue. On MRI, lipomas demonstrate high signal intensity on T1W and FSE T2W images without contrast enhancement and weak signal on fat-suppressed images. Fine needle aspiration may be performed as part of a parotid mass work-up. However, this may not always provide a diagnosis. Surgical excision is the definitive treatment with surgical approach tailored to the lipoma's characteristics/location. Surgical excision can be challenging as the proximity of the facial nerve requires meticulous surgical dissection.1 Recurrence after surgical excision is rare.2
1. Wu C-W, Chi H-P, Chiang F-Y, Hsu Y-C, Chan L-P, Kuo W-R. Giant lipoma arising from deep lobe of the parotid gland. World Journal of Surgical Oncology. 2006;4:28.
2. Mesolella M, Ricciardiello F, Oliva F, Abate T, Lullo A, Marino A. Parotid Lipoma: A Case Report. Case Reports in Clinical Medicine. 2014;3:437-442.
3. Dispenza F, De Stefano A, Romano G, Mazzoni A. Post-Traumatic Lipoma of the Parotid Gland: Case Report. Acta Otorhinolaryngologica Italic. 2008;28:87-88.