Solitary fibrous tumor of the carotid sheath.

A 76-year-old woman was found to have a palpable, asymptomatic left neck mass during an annual physical examination. The patient was referred for further workup. She denied any weight loss, lethargy, pain, otalgia, dysphagia, odynophagia, fever, or voice changes. Her medical history was significant only for smoking; prior to quitting 20 years earlier, she had smoked 2 packs of cigarettes per week for 42 years.

The neck mass measured 3 x 4 cm. It was pulsatile and much more mobile in the horizontal plane than in the vertical plane. Magnetic resonance imaging (MRI) demonstrated a 4.0 x 2.6 x 1.8-cm heterogeneously enhancing, circumscribed mass between the internal jugular vein and the carotid bulb (figure 1). No other mass or adenopathy was noted. An image-guided needle biopsy was performed, and the aspirate was hypocellular. Positron-emission tomography revealed no abnormal metabolic activity in the neck.

[FIGURE 1 OMITTED]

High on the list of working differential diagnoses were glomus vagale, schwannoma, neurofibroma, squamous cell carcinoma, and carotid body tumor. Magnetic resonance angiography was performed in an attempt to better evaluate the vascular character of the tumor, and the findings were not suggestive of a carotid body tumor. The results of a diagnostic endoscopy were negative.

The mass was removed during an uneventful excision (figure 2). Histologically, it appeared as a benign spindle cell neoplasm arranged in fascicles in prominent hyalinized stroma (figure 3, A). The tumor was morphologically consistent with a solitary fibrous tumor. This finding was supported by the results of immunohistochemical staining, which was positive for CD34 (figure 3, B), bcl-2, and vimentin and negative for S-100, smooth-muscle actin, desmin, and keratin AE1/AE3.

[FIGURES 2-3 OMITTED]

Solitary fibrous tumors are neoplasms of mesenchymal origin. Most of these tumors arise from the pleura, but they have also been reported in extrapleural sites such as the lung, mediastinum, pericardium, peritoneum, meninges, and the head and neck. (1) Head and neck sites reported in the literature include the nasal cavity, retropharynx, buccal mucosa, maxillary sinus, parapharyngeal space, larynx, thyroid, and infratemporal fossa. (1-3) To our knowledge, no solitary fibrous tumor arising in the carotid sheath has been reported until now.

Solitary fibrous tumors exhibit no characteristic clinical and radiologic features, so they cannot be reliably diagnosed prior to surgical excision. Kim et al described the MRI features of solitary fibrous tumors of the head and neck in a review of six cases. (1) They found that these neoplasms were isointense to muscle on contrast-enhanced T1-weighted imaging and hyperintense on T2-weighted imaging. However, they also noted some variation on T2-weighted imaging that correlated with the density of collagen and fibroblasts within each tumor.

Histopathologic evaluation with immunohistochemical staining is necessary to make a definitive diagnosis. Surgical resection is classically both diagnostic and curative. Although solitary fibrous tumor of the head and neck is uncommon, it should be included in the differential diagnosis of an isolated neck mass.

References

(1.) Kim HJ, Lee HK, Seo JJ, et al. MR imaging of solitary fibrous tumors in the head and neck. Korean J Radiol 2005;6:136-42.

(2.) Jham BC, Salles JM, Soares JM, et al. Solitary fibrous tumour of the buccal mucosa: Case report and review of the literature. Br J Oral Maxillofac Surg 2005 Dec 19 [Epub ahead of print].

(3.) Casani AP, Marchetti M, Dallan I, et al. Extensive solitary fibrous tumor of the retropharyngeal space. Head Neck 2006;28:270-4.

Ryan F. Osborne, MD, FACS

From the Head and Neck Cancer Center, Cedars-Sinai Medical Center, and the Osborne Head and Neck Institute, Los Angeles.