Volume 4, Issue 1 , Pages 45-48, January 2009
Retropharyngeal fibrolipoma: A counterchanging obstructive pattern in sleep apnea
Article Outline
Summary
Retropharyngeal fibrolipoma has rarely been reported as the cause of obstructive sleep apnea (OSA). The clinical presentation, diagnosis, and treatment of tumor-related OSA are vastly different from those of generic OSA. We report a case of retropharyngeal fibrolipoma in a 17-year-old boy. Our patient presented with snoring, daytime sleepiness, and difficulty in swallowing. Flexible fiberoptic nasopharyngoscopy revealed a smooth bulging mass in the retropharynx. Magnetic resonance imaging demonstrated a hyperintense, heterogeneous mass over the retropharynx. Transoral excision of the retropharyngeal tumor was performed and pathological examination proved the tumor to be a fibrolipoma. The apnea/hypopnea index decreased from 12.2 to 7.4
event/h after surgery with associated improvement in snoring, daytime sleepiness, and swallowing. When swallowing difficulty occurs in patients with OSA, the retropharyngeal obstruction should be considered in evaluating the patient.
Keywords: Retropharyngeal fibrolipoma, Lipoma, Obstructive sleep apnea
1. Introduction
Obstructive sleep apnea (OSA) is characterized by episodes of complete or partial obstruction of the upper airway during sleep. The levels of obstruction vary from the nose to the larynx, but the most common locations are in the soft palate and tongue base. Retropharyngeal obstruction has been reported to contribute to adult OSA, although the incidence is very low [1], [2], [3], [4]. The posterior to anterior obstruction at the retropharynx is very different from the usual obstructive pattern, which is anterior to posterior and lateral to central in OSA patients. The distinct obstruction pattern may lead to a different clinical presentation, diagnosis, and treatment modality. We present a patient with retropharyngeal fibrolipoma causing OSA and review the published data on this rare condition.
2. Case report
A 17-year-old boy had no remarkable medical history. He was of medium build (height 166cm; weight 58kg) with body mass index of 21 (kg/m2). The patient complained of snoring, progressive swallowing disturbance, poor quality of sleep, and excessive daytime sleepiness for 3 months. Routine oral examination revealed small tonsils with clear palate/tongue position. Flexible fiberoptic nasopharyngoscopy showed a smooth bulging over the retropharynx with significant narrowing of the pharyngeal lumen (Fig. 1A). Sagittal T1-weighted magnetic resonance imaging (MRI) revealed a 5cm×3cm×3cm heterogeneous solitary submucosal mass at the retropharyngeal space, narrowing the oropharynx (Fig. 2A). Lipoma, lipoblastoma, and teratoma were considered in the differential diagnosis. Polysomnography showed mild OSA syndrome with an apnea/hypopnea index (AHI) of 12.2event/h. Transoral excision of the retropharyngeal mass was performed after the patient received a general anesthetic through orotracheal intubation. We initially created a superior-based U-shaped mucosa flap overlying the retropharyngeal mass and dissected it from surrounding soft tissue. In the end, the wound was closed primarily with 2–0 Dexon sutures. Grossly, the mass was soft and pinkish with a multilobulated surface (4cm×4cm×1cm). The histopathological examination showed proliferation of mature adipose tissue admixed with fibrous tissue, which led to the diagnosis of fibrolipoma (Fig. 3). The patient's postoperative course was uneventful. After the operation, the patient experienced improvement in snoring, daytime somnolence, sleep quality, and complete resolution of swallowing disturbance. Six months after the operation, polysomnography showed significant improvement in the snoring index from 215.7 to 1event/h, AHI from 12.2 to 7.4event/h, and sleep efficiency from 61.1% to 92.3%. The postoperative flexible fiberoptic nasopharyngoscopy showed significantly increased retropalatal space (Fig. 1B). Postoperative MRI demonstrated a patent airway at the retropharynx and no residual tumor mass (Fig. 2B). There is no evidence of recurrence after 3 years of follow up.
Fig. 1.
(A) Preoperative flexible fiberoptic nasopharyngoscopy shows smooth bulging of retropharyngeal space from posterior to anterior, causing narrowing of the pharynx. (B) Enlarged space of the pharynx after excision of the retropharyngeal fibrolipoma.
Fig. 2.
(A) Preoperative sagittal T1-weighted MRI reveals a heterogeneous solitary submucosal mass at the retropharyngeal space with compression to the tongue base. (B) Expansion of pharyngeal airspace after operation.
Fig. 3.
Histopathological examination showed proliferation of mature adipose tissue admixed with fibrous tissue consistent with fibrolipoma (hematoxylin and eosin stain, original magnification 400×).
3. Discussion
The anatomical narrowing in OSA patients occurs commonly in the soft palate and tongue base. The prevalence of retropharyngeal obstruction contributing to OSA cannot be accurately ascertained because only four English-language reports are available [1], [2], [3], [4].
Baseline data from English-language references about OSA caused by retropharyngeal lipoma are shown in Table 1. Based on examination of the limited sources, the average age of the patient is 51 years old and the male/female ratio is 3:1. The relatively advanced age at which these patients come to medical attention may be due to the slow growth of lipomas and their location in the retropharynx; most are quite large before they are discovered. Our 17-year-old patient was much younger than the average age (51 years) of the reported patient pool and this may reflect the possibility of this disease in young adults.
Table 1. Overview of retropharyngeal lipoma causing obstructive sleep apnea
| Author | Age | Sex | BMI | Symptoms | Tumor size (cm) | Diagnosis | Treatment | AHI (preoperative) | AHI (postoperative) |
|---|---|---|---|---|---|---|---|---|---|
| Aland | 36 | M | N/A | 1, 2, 3, 4, 5, 6 | 8×4×6 | CT | Transoral | N/A | N/A |
| Senchenkov et al. | 49 | F | N/A | 1, 2, 3,4 | 8×5×4 | CT, MRI | Transcervical | 14 | N/A |
| Girolamo et al. | 56 | M | N/A | 1, 2, 3 | 9.5×6×4 | CT, FNA | Transoral | N/A | N/A |
| Hockstein et al. | 64 | M | N/A | 1, 2, 3 | N/A | CT, MRI, FNA | CPAP therapy | 99 | N/A |
| Present case | 17 | M | 21 | 1, 2, 3, 4 | 4×4×1 | MRI | Transoral | 12.2 | 7.4 |
The symptoms of retropharyngeal lipoma may be related to breathing, swallowing, or/and speech depending on the location and size of the mass. In the four previously reported patients (Table 1), OSA-related symptoms such as snoring, daytime sleepiness, and sleep apnea comprise the principal presentation. It is noteworthy that two patients complained of difficulty in swallowing [1], [2] and speech was problematic in one of them [1]. In the case of our patient, a progressive lump in the throat and difficulty in swallowing were noted. These manifestations are rarely experienced by OSA patients with airway collapse in the soft palate and tongue and are obviously due to the mass in the retropharynx interfering with the normal swallowing and speaking processes. Consequently, any associated swallowing and/or speech dysfunction in OSA patients could imply [or implies] unusual patterns of obstruction, and retropharyngeal obstruction should be taken into account.
Space-occupying lesions in the retropharynx of OSA patients are easily missed in a physical examination performed from the front. Flexible fiberoptic nasopharyngoscopy serves as a safe and convenient utility to assess the pharynx. In this case, a smooth mass beneath the posterior pharyngeal mucosa was clearly demonstrated (Fig. 1A), which also indicated the necessity of an imaging study to identify the nature and extension of the retropharyngeal mass. On computed tomography (CT), a lipoma is seen as a homogeneous, low-attenuation mass with sharp demarcation from surrounding tissue. By contrast, a hyperintense soft tissue mass is compatible with a fat signal on MRI. In our patient, sagittal T1-weighted MRI demonstrated a hyperintense mass over the retropharynx with heterogeneous content that could be due to the mixture of adipose and fibrous components. However, the possibility of liposarcoma or lipoblastoma cannot be excluded in this circumstance. Although fine needle aspiration can offer cytological evidence before surgery, its diagnostic ability is limited by inadequate sampling. Consequently, we suggest providing further imaging studies (MRI or CT) to facilitate the diagnosis for retropharyngeal mass causing OSA.
The standard management of OSA is continuous positive airway pressure therapy. OSA caused by a retropharyngeal lipoma should be treated as a space-occupying tumor. The tumor will usually need to be excised to improve not only sleep apnea-related symptoms but also associated swallowing and speech problems. Surgical routes to resect a retropharyngeal mass include the transcervical and transoral approach. The transcervical approach provides a better surgical field, whereas the transoral approach is believed to provide the patient with easier recovery, shorter hospital admission period, and no postoperative scar on the neck.
The improvement of OSA-related symptoms after removal of a retropharyngeal lipoma is significant [1], [2], [3], [4]. To our knowledge, there are no reports of polysomnographic change after surgery for retropharyngeal lipoma in previous literature. Our patient had a decrease in AHI from 12.2 to 7.4event/h, associated with resolution of OSA-related symptoms and swallowing problems. The results suggest that excision of a retropharyngeal lipoma leads to a great improvement in OSA. Because there is the possibility of relapsing OSA in the future for these patients due to increased age and body weight or recurrent lipoma, they need long-term follow up.
4. Conclusion
Benign retropharyngeal tumor, although rare, can still cause OSA. Associated swallowing and speech disturbances differentiate these patients from ordinary OSA patients with obstruction in the level of soft palate and tongue base. Imaging studies such as CT scanning or MRI can be helpful in concluding the diagnosis. Excision of the tumor leads to a significant improvement in OSA; however, these patients need long-term follow up because recurrence of lipoma is possible in the future.
References
- . Retropharyngeal lipoma causing symptoms of obstructive sleep apnea. Otolaryngol. Head Neck Surg. 1996;114:628–630
- . Radiographic assessment of the infiltrating retropharyngeal lipoma. Otolaryngol. Head Neck Surg. 2001;125:658–660
- Retropharyngeal lipoma causing sleep apnea syndrome. J. Oral Maxillofac. Surg. 1998;56:1003–1004
- Retropharyngeal lipoma causing obstructive sleep apnea: case report including five-year follow-up. Laryngoscope. 2002;112:1603–1605
PII: S1871-4048(08)00044-0
doi:10.1016/j.pedex.2008.06.002
© 2008 Elsevier Ireland Ltd. All rights reserved.
Volume 4, Issue 1 , Pages 45-48, January 2009
