A giant retropharyngeal space lipoma: a case report and review of the literature.

Background: Lipoma is the most common benign mesenchymal tumor; however, its occurrence in the retropharyngeal space (retropharyngeal lipoma [RPL]) is exceedingly rare. Due to the softness and distensibility of the retropharyngeal space, RPLs can enlarge significantly without causing any symptoms, resulting in wide variability in tumor size at diagnosis. Although tumor size inevitably influences symptom burden and treatment strategies, no review has focused specifically on "giant" RPLs. Herein, we report a case of exceptionally large RPL and review previously reported giant cases with a maximum diameter of ≥ 10 cm. Case presentation: A 55-year-old Japanese male presented with mild dyspnea, progressive dysphagia, anterior neck swelling, and long-standing worsening snoring. Endoscopy demonstrated submucosal bulging of the posterior pharyngeal wall. Computed tomography revealed a well-circumscribed, non-enhanced, fat density mass measuring 140 × 110 mm in the retropharyngeal space, extending from the level of the uvula to the lower pole of the thyroid and displacing the pharyngolarynx, trachea, esophagus, thyroid gland, and common carotid arteries. An imaging diagnosis of RPL was confirmed by magnetic resonance imaging. Given the enormous size and anticipated risk of postoperative airway compromise, transcervical resection with prophylactic tracheostomy was performed using a nerve integrity monitor (NIM). The excised tumor measured 145 × 120 × 40 mm and weighed 240 g. Histopathological findings further corroborated the diagnosis of lipoma. Postoperatively, oral intake gradually normalized, and all preoperative symptoms fully resolved within two months. Conclusions: This case highlights the need to recognize giant RPL as one of the differential diagnoses in patients with gradually worsening dysphagia and the efficacy of its surgical treatment. A literature review of giant RPL cases suggested an even higher predominance in males, a greater symptom multiplicity, and a more frequent use of the transcervical approach. NIM was considered useful in this case as an adjunct for locating the recurrent laryngeal nerve, while the necessity of prophylactic tracheostomy and postoperative tube feeding should be assessed individually.