There are 3 fascia layers in the retropharyngeal area: the oropharyngeal layer, the buccopharyngeal fascia, and the prevertebral fascia. The retropharyngeal space lies between the buccopharyngeal fascia and the prevertebral fascia, and extends from the skull base to the mediastinum. The prevertebral space is located between the prevertebral fascia and the vertebra, and extends from the skull base to the 3rd thoracic vertebra. Patients with liposarcoma are usually asymptomatic unless the tumor grows to an enormous size causing cosmetic deformity or pressure effects. Also, symptoms vary depending on the anatomical location and size of the tumor. Retroperitoneal liposarcomas are usually asymptomatic due to the anatomic location. When a retroperitoneal liposarcoma grows to an extremely large size, it can present as an asymptomatic abdominal mass or cause pressure symptoms such as abdominal pain/fullness, flank pain or early satiety. Complete surgical resection with negative microscopic margins is the main treatment for retroperitoneal liposarcoma. Even with grossly complete resection, the disease has a high recurrence rate and a poor prognosis. Thus, long-term follow-up appointments are required (2).
Liposarcomas in the retropharyngeal space can produce pressure symptoms such as dysphagia, dyspnea and dysphonia. As the retropharyngeal and prevertebral spaces are adjacent, prevertebral tumors can cause similar symptoms. As the fascia layers cannot be directly seen in the images, and the anatomic locations of the retropharyngeal space and prevertebral space are adjacent, it is difficult to distinguish between retropharyngeal and prevertebral tumors using imaging. The primary tumor site can be estimated based on the surrounding structures of the tumor, such as the posterior pharyngeal space fat, the prevertebral muscle and the carotid sheath. For instance, retropharyngeal tumors often cause prevertebral muscles to move inward, while prevertebral tumors often cause prevertebral muscles to move forward. Further, retropharyngeal tumors are often confined to the left or right side. As the retropharyngeal space is divided into left and right sides by the pharyngeal raphe at the midline, the 2 sides are not connected to each other. However, if the retropharyngeal tumor is enormous, it may not be confined to 1 side, and the features of the surrounding structures may not be clear. In this situation, liposarcoma of the prevertebral space may sometimes be misdiagnosed as retropharyngeal liposarcoma. Therefore, surgery may be the only way to distinguish between enormous retropharyngeal and prevertebral tumors. Thus, in our view, it is not necessary to focus on differentiating between enormous retropharyngeal and prevertebral tumors.
Although a preliminary diagnosis of liposarcoma can be made by CT or MRI, pathology and immunohistochemistry examinations are still needed for diagnostic confirmation. Due to the small number of cases of liposarcoma of the head and neck, the management of these tumors has largely been based on experience with limb and retroperitoneal tumors. The main treatment for liposarcoma is surgical excision with adequate margins (2). However, given the abundance of complex and vital neurovascular and functional upper-aero digestive structures, attaining adequate margins in the head and neck region is difficult. Further, for a liposarcoma in lymph nodes with a relatively low metastasis rate, routine neck dissection is not recommended. It is our view that transoral surgical excision with the assistance of a nasal endoscope may be more beneficial than the cervical approach. The indication for adjuvant radiation therapy is still unclear, some authors (3) believe that wide surgical excision alone is sufficient for successful treatment. However, others (4-6) have recommended adjuvant radiotherapy, as they believe that liposarcomas often infiltrate the surrounding structures microscopically, even if they have a clear fibrous capsule. In the present case, the patient was advised that the tumor may recur, but he refused to undergo adjuvant radiotherapy, as he could not afford follow-up treatment. At 3 months after the surgery, we performed a CT scan of the neck to evaluate the patient’s condition and found no signs of recurrence (Fig. 2B). At 1-year after the initial surgical procedure, the patient continued to do well, and there was no evidence of recurrence. Thus, in terms of the short-term outcome, we believe complete excision using the transoral approach may be a good choice to treat liposarcoma in the prevertebral space, especially in patients of advanced age.