Rhabdomyoma of the larynx: case report and clinical and pathologic review.

Abstract

We describe a case involving a 79-year-old man with symptoms of slowly progressive hoarseness resulting from a rhabdomyoma originating deep to the right true and false vocal folds. We also review the pathology and radiologic findings of rhabdomyoma.

Introduction

Rhabdomyoma is a rare tumor originating in striated muscle, most commonly in the heart. Extracardiac rhabdomyomas most commonly occur in the head and neck region, usually in the upper aerodigestive tract. (1) Two types of extracardiac rhabdomyomas in the head and neck region have been identified: fetal and adult. These lesions are benign, and their clinical course reflects their slow growth. Patients often present with progressive dysphagia, hoarseness, dyspnea, or foreign-body sensation. Treatment depends on accurate diagnosis, and complete excision of the tumor with preservation of the surrounding tissues is usually curative. Tumor recurrence should alert one to the possibility of rhabdomyosarcoma but more often is associated with incomplete excision.

Laryngeal rhabdomyoma is an extremely rare tumor presenting most often in men older than 40 years, but it must be considered in the differential diagnosis of laryngeal neoplasms. We present a case of an adult noncardiac rhabdomyoma of the larynx in an elderly man and review the typical treatment of rhabdomyomas for the otolaryngologist.

Case report

A 79-year-old man presented with progressive hoarseness of 5 years' duration. He had biopsy-proven rhabdomyoma of the submucosal larynx and was referred to our institution by an outside otolaryngologist. The patient had no complaints of airway obstruction or dysphagia. Medical history was significant for rate-controlled atrial fibrillation (for which he was receiving warfarin), valvular disease, and previous tobacco abuse. Examination showed a well-developed man in no apparent distress, breathing quietly without stridor. His voice was very hoarse but intelligible. Flexible fiberoptic laryngoscopy revealed a submucosal mass in the region of the right vocal fold. Abduction and adduction of the vocal folds were normal; however, the view of the right true vocal fold was partially obstructed by the lesion. The left vocal fold appeared normal. The glottic airway opening was reduced by approximately 30%.

Computed tomography (CT) showed a 2 x 1.7-cm submucosal mass originating from the false vocal fold and extending to the laryngeal framework and down to the upper trachea region. No cartilage erosion was seen (figure 1).

[FIGURE 1 OMITTED]

Direct laryngoscopy under general anesthesia revealed right false-vocal-fold submucosal fullness. The mass appeared to be too large for endoscopic laser resection (figure 2). External excision was performed though a window in the midportion of the right side of the thyroid cartilage. Upon incision of the internal perichondrium, a white lesion with the consistency of adipose tissue was well apparent and easily accessible. The mass was not encapsulated. A frozen section of this tissue confirmed the previous diagnosis of rhabdomyoma. The tumor was carefully teased off the surrounding tissue until no further gross tumor was noted. There was no obvious penetration of the laryngeal mucosa. A Penrose drain was placed in the wound and sutured to the skin. Alter closure of the surgical wound, a second direct laryngoscopy revealed intact piriform sinuses and laryngeal mucosa bilaterally, as well as a significant reduction of the submucosal fullness of the right false-vocal-fold, ventricle, and true-vocal-fold region (figure 3).

[FIGURES 2-3 OMITTED]

The patient was left intubated overnight because of the potential for swelling, for which he also was given intra venous steroids. Final pathologic diagnosis revealed rhabdomyoma, adult type (figure 4).

[FIGURE 4 OMITTED]

The patient was extubated the next morning and the Penrose drain removed. His postoperative course was complicated by subcutaneous emphysema and edema extending from the neck to the right periorbital area. Repeat fiberoptic nasolaryngoscopy showed bilateral mobility of the true vocal folds and no obvious laryngeal mucosal tears. A gastrograffin swallow study showed an intact esophagus and piriform sinus mucosa. The Penrose drain was replaced, and the patient was put on strict voice rest and nasogastric tube feedings. With this treatment, the emphysema fluctuated but gradually improved over the next few days. His diet was advanced to oral nutrition on postoperative day 7. The subcutaneous emphysema decreased to near-resolution by postoperative day 10, when the patient was discharged home on a regular diet. He has done well, with continuing resolution of hoarseness at the 6-week follow-up.

Discussion

Extracardiac rhabdomyoma is a rare benign tumor of striated muscle origin that is found in adults and children. It is considered distinct from cardiac rhabdomyoma, which is believed to be a hamartoma and not a true neoplasm and which is usually diagnosed in children and associated with tuberous sclerosis. (2) Extracardiac rhabdomyoma can be classified into fetal, genital, and adult types. (3) Genital rhabdomyomas are lesions found in the vulva or vagina in young or middle-aged women. Fetal rhabdomyoma can be further subdivided into myxoid and cellular types.

Myxoid fetal rhabdomyomas occur most often in the subcutaneous tissues of the head and neck, especially in the postauricular region of male infants under 3 years of age. They occur exceedingly rarely in the larynx. (4)

Histologically, these rhabdomyomas consist of a mixture of elongated, spindle-shaped, or oval cells with indistinct cytoplasm and muscle fibers that resemble the striated muscle tissue seen in intrauterine development at 7 to 12 weeks. Immunohistochemistry staining is positive for desmin and vimentin and is less dense for myoglobin than in adult rhabdomyoma. (5)

Cellular fetal rhabdomyomas occur primarily in the head and neck region of adult men. (6) Histologically, they are more cellular than the myxoid type and contain elongated, spindly, immature skeletal-muscle cells with scant stroma.

Adult rhabdomyomas are found almost exclusively in patients older than 40 years and occur in men three times more often than in women. (7) They appear most often in the region of the base of the tongue, floor of the mouth, larynx, and pharynx. Uncommon locations include the soft palate, uvula, lip and cheek, orbit, esophagus, stomach, and mediastinum. (8-13)

Clinically, adult rhabdomyomas present with slowly progressive symptoms because of their slow growth and benign nature. Depending on the location of the tumor, patients may present with progressive hoarseness, dysphagia, airway obstruction, a palpable mass, or serous otitis media from eustachian tube obstruction.

On gross pathology, adult rhabdomyomas are reddish-brown or gray, lobulated, and soft. (6) Histologically, they are characterized by the presence of sheets of large ovoid or polygonal cells with eosinophilic cytoplasm. (3) The nucleus is large and peripherally placed, with small nucleoli, and the cytoplasm may be granular or vacuolated because of the presence of glycogen. Cytoplasmic cross-striations are difficult to identify on routine hematoxylin and eosin sections but can be identified in some cases with a phosphotungstic acid hematoxylin. (11) Most cells can be immunostained with antibodies to muscle-specific actin, desmin, and myoglobin, which are markers of mature muscle cells. Of note, immunostaining for vimentin is negative. (5) Mitoses are typically absent, as well. Ultrastructural features consist of hypertrophic Z bands, intranuclear inclusions, and numerous mitochondria with linear intracristal inclusions. (14)

Histologically, our patient's neoplasm showed the classic features of adult rhabdomyoma: differentiated skeletal muscle composed of large, round to oval cells with pale, pink-staining, finely granular cytoplasm. The cells were vacuolated, and cross-striations were found in a few cells.

Radiographically, adult rhabdomyomas appear as benign neoplasms. Features that differentiate them from malignant lesions include well-circumscribed margins, absence of invasion of surrounding soft tissues, and submucosal locations. (15) However, cases have been reported in which rhabdomyomas mimicked malignant lesions on CT imaging, with indistinct borders blending into the adjacent isodense muscle. (16) Magnetic resonance imaging may help to delineate the extent and location of tumor involvement. On T1- and T2-weighted images, rhabdomyomas are isointense or slightly hyperintense to muscle, and they homogeneously enhance without necrosis or hemorrhage. (17)

Diagnosis. The differential diagnosis for laryngeal masses includes cysts, laryngoceles, and malignant neoplasms such as squamous cell carcinoma and rhabdomyosarcoma, as well as benign neoplasms such as hemangiomas, lipomas, amyloidomas, neurofibromas, granular cell tumors, leiomyomas, and rhabdomyomas. (15)

Rhabdomyosarcomas, although grossly similar to rhabdomyomas, usually present in peripheral skeletal musculature and not in the larynx or pharynx, and symptoms progress much more rapidly. (6,18) Microscopically, rhabdomyosarcoma can be distinguished by the presence of atypical mitotic figures, nuclear pleomorphism, and foci of invasion.

Granular cell tumors, although typically occurring in the larynx, can be quite readily distinguished from rhabdomyomas histologically. Granular cell tumors are composed of nests and cords of small, round to polygonal cells possessing a cytoplasm with an abundance of acidophilic granules, which gives the tumor a foamy appearance. (19,20) The nuclei are small and centrally located, with inconspicuous nucleoli and no evidence of myofilamentary differentiation. (6)

Therapy. Treatment of rhabdomyoma consists primarily of complete excision with preservation of the surrounding tissues. Recurrences are most commonly associated with incomplete excision and have been reported to occur in more than one-third of cases. (7) Follow-up must be longterm, as recurrence can occur after as long as 35 years. Tumor recurrence also should alert one to the possibility of rhabdomyosarcoma.

References

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(19.) Goodstein ML, Eisele DW, Hyams VJ, Kashima HK. Multiple synchronous granular cell tumors of the upper aerodigestive tract. Otolaryngol Head Neck Surg 1990;130:664-8.

(20.) Lazar RH, Younis RT, Kluka EA, et al. Granular cell tumor of the larynx: Report of two pediatric cases. Ear Nose Throat J 1992;71 440-3.

From the Department of Otolaryngology Head and Neck Surgery (Dr. Brys, Dr. DeRosa, and Dr. Shapshay) and the Department of Radiology (Dr. Sakai), Boston Medical Center, Boston University School of Medicine.

Reprint requests: Agata K. Brys, MD, Department of Otolaryngology--Head and Neck Surgery, Boston University School of Medicine, 715 Albany St., (7-608, Boston, MA 02118. Phone: [phone]; fax: [phone]; e-mail: [e-mail].