Pathology Quiz Case 1

Abstract

A 10-YEAR-OLD GIRL PRESENTED WITH A 4-month history of a large oropharyngeal mass and a left-side upper neck mass that remained stable in size since its discovery. The patient complained of dysphagia without significant weight loss but denied dyspnea, dysphonia, or otalgia. The patient was otherwise healthy, up-to-date on immunizations, and had no prior tobacco exposure. On examination, a well-mucosalized, nonfluctuant, firm mass was palpable on the left side of the base of the tongue, causing leftward deviation of the tongue. There was also a palpable level II neck mass that was contiguous on bimanual palpation intraorally with no other cervical lymphadenopathy. Computed tomography (CT) of the neck revealed a nonenhancing, well-circumscribed, solid 4.3 2.73-cm mass in the region of the sublingual space and tongue base, displacing the sublingual and submandibular glands. The mass appeared contiguous with the tongue musculature and exhibited several dystrophic calcifications. Magnetic resonance imaging (MRI) with gadolinium was obtained to further characterize the lesion shown in Figure 1. Grossly, the mass was well circumscribed, with a thin capsule, and was firm and pale tan in color. Histopathologic findings of the specimen in hematoxylin-eosin stain are shown at both low and high magnifications (original magnification 10 and 20, respectively) in Figure2 and Figure 3, respectively. In the background, prominent thin-walled capillaries were found on CD34 staining. The collagenous cores stained positive for vimentin and negative for desmin, smooth muscle actin, S-100, CD34, anaplastic lymphoma kinase, and epithelial membrane antigen (EMA). Fluorescence in situ hybridization (FISH) using a FUS gene rearrangement probe applied to formalin-fixed, paraffin-embedded tissues is shown in Figure 4. What is your diagnosis?