AJR 2000; 174:1285-1287
© American Roentgen Ray Society
Laryngeal Rhabdomyoma Involving the Paraglottic Space
Grace S. Liang1,
Laurie A. Loevner and
Priya Kumar
1
All authors: Department of Radiology, University of Pennsylvania School of
Medicine, University of Pennsylvania Medical Center, 3400 Spruce St.,
Philadelphia, PA 19104.
Received August 17, 1999;
accepted after revision October 18, 1999.
Supported by the Radiological Society of North America Research and
Education Fund Scholar Grant.
Address correspondence to L.A. Loevner.
Introduction
Extracardiac rhabdomyomas are rare benign tumors that originate from
striated muscle. Because of their slow growth, these tumors frequently grow
very large before they become symptomatic. We describe a 39-year-old man with
progressive dysphagia and airway compromise resulting from a rhabdomyoma
originating in the left-sided paraglottic space. We discuss the radiologic
features that suggested that this tumor was benign rather than malignant.
Rhabdomyomas arising from striated muscle are uncommon compared with their
malignant counterparts, rhabdomyosarcomas, and account for only 2% of all
striated muscle tumors [1]. Two
forms of rhabdomyomas exist: cardiac and extracardiac. Investigators postulate
that cardiac rhabdomyomas are hamartomatous lesions because of their
association with syndromes such as tuberous sclerosis
[1]. In contrast, extracardiac
rhabdomyomas represent true neoplasms. Fewer than 200 extracardiac
rhabdomyomas have been reported. Tumors arising in the head and neck usually
originate from the musculature of the pharynx, oral cavity, or larynx
[2]. We describe a patient with
a laryngeal rhabdomyoma involving the paraglottic space and discuss the
radiologic findings that help to differentiate this rare entity from malignant
masses of the upper aerodigestive tract.
Case Report
A 39-year-old man presented to our institution with a 5-month history of
dysphagia, episodes of aspiration, and a 14-lb (6.3-kg) weight loss during the
6-month period before admission. The patient's medical history included anoxic
brain injury as a child, resulting in mental retardation and a seizure
disorder. The patient also had gastroesophageal reflux and Barrett's
esophagus. On physical examination, the patient was cachectic without a
palpable neck mass or lymphadenopathy. Nasopharyngeal laryngoscopy was
performed, at which time the larynx was not well visualized because of a large
submucosal mass that partially obstructed the airway lumen.
Contrast-enhanced CT of the neck revealed a well-demarcated diffusely
hyperattenuating submucosal mass involving the left-sided paraglottic space
(Figs. 1A and
1B). The mass narrowed the
airway lumen and extended from the left-sided aryepiglottic fold of the
supraglottis to the left-sided true vocal cord. The remainder of the neck
appeared normal without lymphadenopathy. The mass appeared slightly
hyperintense to muscle on T1- and T2-weighted MR images and had mildly diffuse
enhancement after the administration of IV gadolinium (Figs.
1C,1D,1E).
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Fig. 1A. —39-year-old man with laryngeal rhabdomyoma involving paraglottic
space. Contrast-enhanced CT scan of neck at level of supraglottis shows
submucosal mass (open arrows) at level of left-sided aryepiglottic
fold. Note deviation of airway from left to right (curved arrow) and
partial effacement of left-sided piriform sinus (arrowhead).
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Fig. 1B. —39-year-old man with laryngeal rhabdomyoma involving paraglottic
space. Contrast-enhanced CT scan obtained 1 cm below A shows
preservation of fat plane (arrows), demarcating mass from mucosal
surface, and submucosal location. Note superior extension of laryngeal
rhabdomyoma that involves left-sided paraglottic space.
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Fig. 1C. —39-year-old man with laryngeal rhabdomyoma involving paraglottic
space. Unenhanced axial T1-weighted MR image (TR/TE, 400/9; number of
excitations, two) shows submucosal mass (open arrows) mildly
hyperintense to adjacent muscle. Note how indistinct margins of mass blend
into adjacent prevertebral musculature (arrow).
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Fig. 1D. —39-year-old man with laryngeal rhabdomyoma involving paraglottic
space. Axial T2-weighted MR image (2500/90; number of excitations, two)
obtained at same level as C shows mass hypointense to cerebrospinal
fluid and mildly hyperintense to muscle. Mass has uniform signal
characteristics.
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Fig. 1E, —39-year-old man with laryngeal rhabdomyoma involving paraglottic
space. Axial enhanced T1-weighted MR image (400/9; number of excitations, two)
obtained at same level as C and D shows mild homogeneous
enhancement of submucosal mass. Note rim enhancement (arrows) of
lesion. Administration of contrast material aids in demarcating mass from
adjacent posterior musculature.
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Direct intraoperative laryngoscopy with open biopsy was performed after
tracheostomy to protect the airway. Surgical assessment revealed a large
left-sided submucosal mass that caused fullness and medial deviation of the
aryepiglottic fold and bulging of the false cord extending to the laryngeal
ventricle. Pathologic examination revealed round polygonal cells with abundant
eosinophilic finely granular cytoplasm and peripherally placed vesicular
nuclei with small nucleoli. No necrosis or mitoses were noted, and
immunostaining of the tumor cells revealed findings positive for myoglobin and
desmin. These histologic features were consistent with the diagnosis of
adult-form rhabdomyoma. Subsequently, the mass was resected without
complications.
Discussion
Benign masses of the upper aerodigestive tract include nonneoplastic
lesions and tumors. Patients may present with a foreignbody sensation or a
painless neck mass. They may experience dysphagia, dyspnea, voice changes,
cough, or stridor. Rarely, asymptomatic masses are detected in patients
examined for unrelated reasons.
Nonneoplastic lesions include cysts and laryngoceles. Cysts may be
congenital or acquired from trauma or inflammation. Mucous retention cysts
(which may contain proteinaceous inspissated secretions) result from
obstructed minor salivary glands or mucous glands that develop anywhere in the
upper aerodigestive tract but are especially common in the supraglottis.
Laryngoceles represent an outpouching from the laryngeal ventricle into the
paraglottic space caused by obstruction of the ventricular saccule, the
superolateral extension of the ventricle. Laryngoceles are most often caused
by inflammation, adhesions, or instrumentation. Less commonly, they are
associated with laryngeal cancer
[3]. On imaging, laryngoceles
appear as air- or fluid-filled lesions in the paraglottic space.
Malignant neoplasms of the larynx are more common than benign tumors. The
most common epithelial malignancy is squamous cell carcinoma. Less common
malignancies include mesenchymal tumors, such as rhabdomyosarcomas. These
tumors do not respect fascial boundaries. Distant metastases to the lymph
nodes, lungs, and bones are common.
Benign neoplasms of the larynx include hemangiomas, papillomas, and
neurofibromas. Hemangiomas are present in 2.5% of neonates
[4] and may involve the
oropharynx, oral cavity, or larynx. Laryngeal hemangiomas in children are
usually subglottic; laryngeal hemangiomas in adults are supraglottic. The
presence of phleboliths is characteristic of hemangiomas. Papillomas typically
affect the true vocal cords. Neurofibromas may arise from the superior
laryngeal nerve and may secondarily involve the arytenoid muscles and the
aryepiglottic folds. Other rare benign tumors include granular cell tumors,
leiomyomas, and rhabdomyomas. Although benign neoplasms may be
indistinguishable from one another on imaging, they frequently have features
that differentiate them from malignant lesions, including well-circumscribed
margins and submucosal locations.
Rhabdomyomas are rare benign mesenchymal tumors. In its early use, the term
"rhabdomyoma" included a spectrum of pathologically unrelated
neoplasms that contained muscle elements. As the understanding of these
lesions improved, the term rhabdomyoma has come to refer to a group of benign
lesions of striated muscle with mature differentiation. They are categorized
into cardiac and extracardiac lesions, which are believed to be clinically
distinct entities. Cardiac rhabdomyomas are the most common myocardial masses
in children; at least half are associated with tuberous sclerosis. Cardiac
rhabdomyomas are hamartomas and occur in association with hamartomas in other
organ systems.
Extracardiac rhabdomyomas are rare and represent true neoplasms. Most
extracardiac rhabdomyomas occur in the head and neck
[5] and arise from the
pharyngeal constrictor muscles, the floor of the mouth, or the base of the
tongue [1,
2]. Rarely, rhabdomyomas may
arise from the larynx [2,
5]. Two studies have reported
rhabdomyomas in the lateral neck and the orbit
[2,
6]. Extracardiac rhabdomyomas
are usually solitary, but multiple lesions have been reported
[2].
On gross pathology, rhabdomyomas are reddish-brown, lobulated, and soft
[2]. Histologically, these
tumors are further subcategorized into adult and fetal forms according to
their degree of cellular differentiation and maturity. Adult-form extracardiac
rhabdomyomas are composed of closely packed round cells with peripherally
located nuclei. The cells have eosinophilic vacuolated cytoplasm that is
glycogen-rich. Cross-striations (similar to those in mature striated muscle)
are characteristic of rhabdomyomas. Immunostaining reveals positive findings
for muscle-specific actin, desmin, and myoglobin, which are markers of mature
muscle cells. Mitoses are typically absent
[2,
6]. Although isolated cases in
children have been reported, adult-form rhabdomyomas present almost
exclusively in patients older than 40 years. They occur more often in men by a
ratio of 3:1 [6]. Patients may
present with a palpable mass, airway obstruction, dysphagia, foreign body
sensation, hoarseness, or serous otitis media caused by eustachian tube
obstruction [6,
7].
Fetal-form rhabdomyomas are less common than the adult form. They are
composed of immature spindle cells that reveal positive findings on
immunostaining for mature and primitive muscle markers. Rhabdomyomas may have
a highly cellular or myxoid stromal pattern. The myxoid type is more frequent
in boys younger than 3 years and has a predilection for the postauricular
region [1,
2]. The cellular type
frequently affects adults and commonly originates in the head and neck
[2].
Because reported extracardiac rhabdomyomas are rare, their radiologic
appearance has not been well characterized. A barium swallow may show a
pedunculated mass that intermittently obstructs the larynx with respiration,
swallowing, or positional changes. Though these masses may be detected on
radiographs when they obliterate the airway, CT and MR imaging may better
delineate their location and extent. In the few cases reported, rhabdomyomas
may mimic malignant lesions on CT, and appear to have indistinct borders
blending into adjacent isodense muscles
[8]. As in our patient,
contrast administration may aid in identifying the submucosal circumscribed
nature of these lesions (Figs.
1A and
1B). Rhabdomyomas are
isointense or slightly hyperintense to muscle on T1- and T2- weighted MR
images and homogeneously enhance
[7]. Although imaging findings
may not distinguish rhabdomyomas from other benign neoplasms, the absence of
invasion of the surrounding soft tissues, their appearance, and their
submucosal location may differentiate them from malignant lesions. Unlike
malignant lesions, lymphadenopathy and metastases do not occur with these
benign tumors [2].
Treatment of rhabdomyomas requires complete surgical resection. Local
recurrence has been reported in more than one third of cases
[6] and usually results from
incomplete resection. Recurrences may present months to years after initial
resection. Isolated cases of fetal-form rhabdomyoma have been associated with
embryonal rhabdomyosarcoma [1].
To our knowledge, there are no documented cases of malignant degeneration of
adult-form rhabdomyomas
[6].
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Introduction
Case Report
