Retropharyngeal Spindle Cell/Pleomorphic Lipoma
A 69-year-old woman initially presented with a 1-year history of painless swelling on both lateral sides of the neck, which was associated with mild dysphagia and dyspnea. The patient had a history of treatment with surgical and radiation therapies secondary to malignant schwannoma in the right neck about 25 years ago. Laryngoscopic examination revealed a bulging of the posterior hypopharyngeal wall with obliteration of bilateral pyriform sinuses, which suggested a retropharyngeal mass.\nUltrasonography (US) (iU 22 Ultrasound system, Philips Medical System, Bothell, WA, USA) of the patient demonstrated a large heterogeneous mass located in both lateral sides of the neck which was compressing the neck vessels laterally. The mass showed diffuse hyperechogenecity with multiple linear or band-shaped hypoechoic areas (). A contrast-enhanced computed tomography (CT) scan (Somatom Sensation 16, Siemens, Erlangen, Germany) revealed a huge, relatively well defined, heterogeneously hypodense mass, most of which showed minimal enhancement with multifocal low attenuated areas (-15 to -40 Hounsfield unit). The mass was located in the retropharyngeal space extending to both lateral sides of the neck. The tumor displaced but did not infiltrate the adjacent structures (). The maximum dimensions of the entire tumor were 10 × 5 × 11 cm. There was no evidence of associated cervical lymphadenopathy. On magnetic resonance imaging (3.0 Tesla, Verio, Siemens Medical Solution, Erlangen, Germany), most of the mass showed heterogeneously hypointense signal intensity on T1-weighted image (WI) (repetition time [TR] = 750, echo time [TE] = 9.5) and hyperintense signal intensity on fat saturated T2WI (TR = 3950, TE = 89). There were multifocal areas of high signal intensity within the tumor on T1WI, which showed signal loss on fat saturated T2WI (). The tumor extended up to the soft palate level cranially and the thoracic inlet level caudally on sagittal T2WI (TR = 3200, TE = 99) (). After gadolinium administration (0.1 mmol/kg of body weight, omniscan (gadodiamide), GE Healthcare, Oslo, Norway), the mass showed heterogeneous enhancement ().\nThe mass was extirpated by the transcervical approach without complications and was easily separated from the adjacent structures. The patient had immediate amelioration of dysphagia and other symptoms after the operation. The surgical specimen showed a well-circumscribed and lobulated mass with a thin fibrous capsule (). On histologic examination, the tumor showed mostly spindle shaped cells in a collagenous background. Mature adipose tissue and characteristic floret-like multinucleated cells were also present between the spindle cells (). Immunohistochemical staining for CD34 was positive in the spindle shaped cells () and staining for S-100 protein was positive in the mature fat cells ().