Retropharyngeal spindle cell/pleomorphic lipoma

Abstract

Spindle cell/pleomorphic lipoma is an uncommon benign adipose tissue tumor most frequently arising from the subcutaneous tissue of the back, shoulder, head and neck, and extremities. The deep cervical spaces are the rarely affected locations. Herein we report on the imaging findings of spindle cell/pleomorphic lipoma involving the retropharyngeal space in an elderly woman.

Keywords: Magnetic Resonance Imaging; Neoplasms; Retropharyngeal space; Spindle cell/pleomorphic lipoma; Ultrasound: Computed tomography.

Fig. 1

Retropharyngeal spindle cell/pleomorphic lipoma in 69-year-old woman. A. Ultrasonography (left: right side of neck, right: left side of neck) shows large heterogeneous mass (arrows) in both lateral sides of neck, and diffuse hyperechogenecity with multiple linear or band-shaped hypoechoic portions. B. Contrast-enhanced axial CT image shows huge and relatively well defined, minimal enhancing mass, including multifocal low attenuated areas (-15 to -40 Hounsfield unit). Mass is located in retropharyngeal space extending to both lateral sides of neck. Adjacent structures are displaced by tumor, with no evidence of invasion. C-G. On magnetic resonance imaging, mass is observed to have diffusely hypointense signal on T1-weighted image (WI) (C) and hyperintense signal on fat saturated T2WI (D). There are multifocal areas of high signal intensity within mass on T1WI which showed signal loss on fat saturated T2WI (arrows). Mass extends up to soft palate level cranially and thoracic inlet level caudally on sagittal T2WI (E). Fat saturated gadolinium-enhanced axial (F) and coronal (G) T1WI show exceedingly heterogeneous enhancing mass. H. Surgical specimen shows well-circumscribed and lobulated mass with thin fibrous capsule. I. Most of tumor contains spindle shaped cells in collagenous background. Between spindle cells, mature adipose tissue and characteristic floret-like multinucleated cells are present (Hematoxylin & Eosin staining; original magnification, × 10). J. Spindle tumor cells are positive for CD34 (immunohistochemical staining; original magnification, × 10). K. Mature fat cells are positive for S-100 protein. In contrast, spindle cells have no immunoreactivity for S-100 protein (immunohistochemical staining; original magnification, × 10).