Juvenile Nasopharyngeal Angiofibroma.
Juvenile nasopharyngeal angiofibroma (JNA) is the most common type of benign nasopharyngeal tumor, accounting for 0.5% of all head and neck tumors. Although histologically benign, this tumor is clinically aggressive due to its locally invasive growth and extensions into adjacent anatomic regions. It is seen almost exclusively in young male adolescents and has a high incidence of recurrence. Despite the likelihood of recurrence, survival rates have increased greatly due to early diagnosis with advanced technology, including computed tomography and magnetic resonance, and surgical treatment.
Angiofibroma arises from fibrous tissue located in the vault of the nasopharynx. The specific point of origin of the angiofibroma is the posterolateral wall of the roof of the nose, where the sphenoid bone meets the horizontal ala of the vomer and the root of the pterygoid process of the sphenoid. Hormonal imbalance has been thought to be the cause, but there is little evidence to suggest that the tumor regresses with hormone treatment. In addition, spontanteous regression with maturity does not occur in most cases.
Early signs of the tumor are nasal obstruction and profuse, life-threatening nosebleeds. Another common symptom is double vision. With further development of the tumor, hyponasal speech and cheek and palate deformities may occur. Commonly, the symptoms are present for 6 to 12 months prior to a definitive diagnosis. The tumor presents as a red-to-pink, smooth, mucosa-covered, compressible mass located in the nasopharynx.
Pathologically, the tumor is seen as a sessile, lobulated, ovoid mass. It has variable firmness and increased vascularity in the overlying mucosa. The tumor has numerous vascular spaces, generally lined with a single layer of endothelium. Histologically, the overlying mucosa often demonstrate squamous metaplasia. No true capsule exists. The amount of vascular extension into connective tissue varies, and the fibrous elements seem to increase as the patient ages.
Many imaging techniques are used to diagnose JNA, beginning with plain film radiographs. The Water's view of the skull best demonstrates this tumor. Characteristic radiographic findings are:
* Anterior bowing of the posterior wall of the maxillary sinus.
* Opacity of one or more of the paranasal sinuses.
* Erosion of the medial wall of the maxillary sinus and deviation of the nasal septum.
* Erosion of the sphenoid bone with a mass in the sphenoid sinus.
The anterior bowing of the posterior wall of the antrum seen on lateral skull films is known as the Holman-Miller sign and is pathognomonic for JNA. Before the use of CT and MR, radiographs were the primary tool used to diagnose JNA. Even today, skull radiographs may be taken before other imaging techniques are used, due to the cost effectiveness of radiography.
CT began to play a role in diagnosis and staging of this tumor in the 1970s. CT has shown high specificity in identifying the tumor's spread and characteristic bony deformities associated with JNA. CT imaging in both the coronal and axial planes is recommended to best show the exact location of the tumor. The axial projection can demonstrate several characteristics, including a rounded mass within the nasopharynx; tumor extension in the nasal cavity; widening of the pterygopalatine fossa on the side of the tumor; distortion of facial planes in the subtemporal space; indentation of the posterior wall of the antrum by pressure erosion from the tumor mass; and possible invasion of the orbit, sphenoid sinus or middle cranial fossa. Of the above-mentioned characteristics, it is most important to visualize intracranial extensions because they greatly affect the choice of treatment.
Contrast enhancement is recommended for CT examination of this type of tumor. Contrast helps differentiate the extensions of JNA/from normal adjacent tissues or secondarily occluded sinuses. This is particularly helpful in diagnosing invasion into the sphenoid and ethmoid sinuses. JNAs often obstruct the sinuses, causing them to fill with debris and fluid. This can cause the sinuses to have densities that mimic the density of the tumor. With administration of a contrast agent, there is enhancement of the paranasal sinuses that makes it possible to accurately diagnose the extent of invasion. The pattern seen on contrast-enhanced CT is an intensely stained lesion in the nasopharynx with widening of the pterygopalatine fossa. Contrast enhancement also allows the tumor to be located precisely in reference to the medial and lateral pterygoid. Without contrast enhancement, location cannot be determined as precisely. JNAs also have a density quite similar to that of the brain, so it is important to distinguish the tumor from areas of normal anatomy.
Advances in CT technology have contributed to the development of a staging system based on the extent and location of the tumor. This system allows for more accurate and consistent care for patients with JNA. The most widely used and accepted staging system for JNA was developed by R.B. Sessions. (See Table 1.)
Table 1 Staging of JNA Based on the System Developed by Sessions
Stage IA: Tumor limited to the posterior nares and/or nasopharyngeal vault. Stage IB: Tumor involving the posterior nares and/or nasopharyngeal vault with involvement of at least one paranasal sinus. Stage IIA: Minimal lateral extension into the fossa. Stage IIB: Full occupation of the pterygomaxillary fossa with or without superior erosion of orbital bones. Stage IlIA: Erosion of the base of the skull (middle cranial extension). Stage IIIB: Extensive intracranial extension with or without extension into the cavernous sinus.
Whereas CT is most useful in evaluating the bony detail of the craniofacial structures involved with the tumor, MR has the advantage of showing the extension of flow voids into the nasal cavity. MR also may show extensions of the tumor into the cavernous sinus and middle cranial fossa. Along with CT, MR has produced more precise staging results, allowing selection of the best treatment. MR has proven to be a great supplement to CT in diagnosing and staging JNA. (See Figs. 1 and 2.)
[Figures 1-2 ILLUSTRATION OMITTED]
Angiography is useful for determining the tumor's vascular supply and embolizing the tumor preoperatively. The primary blood supply for JNAs is from the internal maxillary artery or the ascending pharyngeal artery. Secondary contributions come from the adjacent tissue as the tumor expands, and both internal and external carotid arterial systems can be involved. (See Fig. 3.)
[Figure 3 ILLUSTRATION OMITTED]
Angiographic studies of these tumors usually include a bilateral selective internal and external carotid angiogram. Transfemoral catheterization of the carotid vessels also can be performed using a transfemoral technique. Before completing the angiogram, special care must be taken to ensure that the entire tumor is visualized with contrast in the vessels. The margins of the tumor should be smooth and sharply delineated. If they are not, additional vessels should be studied. The lack of sharp margins is caused by nonopacified blood supplying the portion of the tumor that has not been visualized.
Before surgery, proper embolization must be performed to prevent massive hemorrhaging from the highly vascular tumor. Biopsy should not be performed on patients with JNA due to the extent of the tumor's vascularity; a biopsy can cause severe hemorrhage resulting in death.
The preferred treatment for angiofibroma is surgery. The main goal is complete surgical removal of the tumor. There are many surgical approaches to the removal of JNA. Because no 2 tumors are alike, neither are the surguries best suited to their removal. Each surgery must be carefully tailored to the size and extent of this aggressive tumor. There have been as many as 65 documented ways to remove JNA, with about 8 logical approaches: transnasal, transpalatal, transmandibular, transzygomatic, transantral through the bed of the hyoid bone, combined craniotomy and rhinotomy and lateral rhinotomy. Of all the surgical approaches, the lateral rhinotomy is the most logical and versatile and allows for best visualization of the tumor. Regardless of the surgical technique, adequate exposure and removal of the entire tumor intact results in minimal residual and recurrent disease. With good preoperative diagnosis of the tumor's extent, surgery can be an excellent treatment for JNA.
Chemotherapy has been used to sucessfully treat selected cases of angiofibroma. Although effective, the use of chemotherapy in JNA is limited mainly to treatment of recurrent lesions when further surgery or radiation is not indicated. This includes cases of intracranial extension with involvement of vital structures and tumors with major blood supply from the intracranial vessels. Although chemotherapy has been effective, it should not be the first treatment choice for JNA.
In conclusion, with advanced diagnostic techniques and treatments, the outlook for adolescent boys with JNA is good. CT is the most commonly used method in evaluating the size and extent of this vascular tumor, replacing conventional radiographs. Recently, MR has played an increasing part in diagnosis of this tumor. Angiography may be performed prior to surgery to help determine the tumor's vascularity. However, biopsy is not recommended due to the tumors' highly vascular nature. Surgery is the most frequent treatment option for JNA and seems to have the best outcome. Radiation therapy and chemotherapy are recommended options for tumors that cannot be completely removed by surgery and for recurrent lesions.
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[2.] Kamel RH. "Transnasal endoscopic surgery in juvenile nasopharyngeal angiofibroma." The Journal of Laryngology and Otology. 1996;110:962.
[3.] Paparella MM, Shumrick DA. Otolaryngology: Head and Neck. Vol. 3. Chicago, Ill: Yearbook Medical Publishers; 1980:2325.
[4.] Healy GB. Common Problems in Pediatric Otolaryngology. Chicago, Ill: Yearbook Medical Publishers; 1990:258.
[5.] Valvassori GE, et al. Radiology of the Ear, Nose and Throat. Boston, Mass: Houghton; 1982:256.
[6.] Ungkanont K, Byers RM, Weber RS. "Juvenial nasopharyngeal angiofibroma: an update on therapeutic management." Head and Neck. 1996;18:64.
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Jody Goodenberger, R.T.(R), completed the radiologic technology program at the University of Nebraska Medical Center in July 1999 and is employed by Nebraska Health Systems. She is continuing her studies in sonography and will receive her bachelor's degree in August.
Pamela J. Ross, B.S., R.T.(T), is editor of this section of the Journal, dedicated to publishing the written works of students in radiologic science educational programs. Ms. Ross is coordinator of technology for radiation oncology at the New York Methodist Hospital in Brooklyn, NY, and chairman of the ASRT Committee on Student Writing Competitions.
Articles published in the "Student Scope" column are eligible to compete for the Mallinckrodt--Radiologic Technology Writing Award. Writing guidelines may be obtained by contacting Dana Bigbie, c/o the American Society of Radiologic Technologists, 15000 Central Ave. SE, Albuquerque, NM 87123-3917.
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|Author:||Goodenberger, Jody; Ross, Pamela J.|
|Date:||Jul 1, 2000|
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