B-ENT, 2013, 9, 77-79 Rhabdomyoma of the pyriform sinus: case report and review of the literature

E. Koudounarakis, A. Kaprana, S. Velegrakis and E. Prokopakis Department of Otorhinolaryngology, University of Crete School of Medicine, Heraklion, Crete, Greece

Key-words. Rhabdomyoma; pyriform sinus; transoral resection

Abstract. Rhabdomyoma of the pyriform sinus: case report and review of the literature. Objective: Adult rhabdomyoma is a rare benign tumour that arises from skeletal muscle. It is mostly found in the head and neck region, and it should be included in the differential diagnosis of benign lesions. Methods: A 62-year-old man presented with dysphagia, and flexible endoscopy revealed a submucosal mass obliterating the right pyriform sinus. Computed tomography imaging revealed that the mass was hyperattenuated and extended from the right pyriform sinus to the true vocal cord. The mass was excised transorally under general anesthesia with a carbon dioxide laser. Microscopically, the tumour demonstrated features of adult-type rhabdomyoma. Results: One year after surgery, the patient had no signs of recurrence. Conclusions: Rhabdomyoma is a rare neoplasm of the pyriform sinus. This entity should be considered in the differential diagnosis of tumours in this region.

Introduction demarcated diffusely hyperattenuating submucosal mass that involved the right pyriform sinus. The Rhabdomyomas are rare, benign tumours that are mass narrowed the airway lumen and extended topographically divided into cardiac and extra­ from the right pyriform sinus to the right true vocal 1 cardiac types. Cardiac rhabdomyomas occur more cord. Magnetic resonance imaging (MRI) of the frequently in children and are mostly associated neck was additionally performed a few days later. 2 with phacomatoses. The extracardiac type is MRI showed a mass surrounded by soft tissue, further­ subdivided morphologically and clinically approximately ­2 cm in diameter, that occupied and into adult, fetal, and genital types, and rhabdo­ obscured the right pyriform sinus, with no cartilage 3 myomatous mesenchymal hamartoma. The adult erosion and no expansion to the parapharyngeal type appears more frequently in the head and neck space (Figure 1). The mass appeared slightly hyper- region, and it is believed to originate from the intense relative to muscle on T1- and T2-weighted skeletal ­muscle of the third and fourth branchial MRI images, and there was mild, diffuse enhance- 3 arches. Most patients are between 40 and 70 years ment after intravenous administration of gadoli­ 4 old. We report a case of pyriform sinus rhabdo- nium. myoma, together with a review of the literature. The patient underwent direct ­laryngoscopy under­ Case report general anesthesia, and the mass was removed through a mucosal incision, with the use of a micro- A 62-year-old man was referred for evaluation; scope and a carbon­ dioxide laser. Histological he had a low-grade fever and throat pain that had examination ­revealed round poly­gonal cells with started 48 hours previously. Clinical examination abundant eosinophilic, finely granular cytoplasm showed erythema of the oropharyngeal mucosa and peripherally placed vesicular nuclei with small with bilateral slight enlargement of some lymph nucleoli. No ­necrosis or mitoses were noted, and nodes, suggestive of viral pharyngitis. Flexible immunostaining of the tumour cells was positive endoscopy­ incidentally revealed the presence of for myoglobin and desmin. These histological fea- a submucosal mass located in the right pyriform tures were consistent with the diagnosis of adult- sinus­; vocal cord function was normal, and there type rhabdo­myoma. were no signs of infection. The postoperative course was uneventful, and A contrast-enhanced computed tomography the patient was discharged on the second post­ (CT) of the neck was performed and showed a well- operative day. One year after surgery, the patient

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Figure 1 Figure 2 Preoperative MRI of the neck, showing a mass (white arrow) MRI of the neck 1 year after surgery of the right pyriform sinus that is slightly hyperintense com- pared to muscle.

was asymptomatic, and endoscopy and MRI of the tal muscle. The tumour consists of polyhedral- hypopharynx did not reveal signs of recurrence to-elongated intensely stained by eosin cells with (Figure 2). bland nuclei, intermingled with cells with clear cyto­plasm.3 The latter may be univacuolated or Discussion multivacuolated, possibly as a consequence of glyco­gen or fat accumulation, which dissolves Extracardiac rhabdomyomas are uncommon neo- during­ tissue processing. The immunohistochemi- plasms of mesenchymal origin; they comprise less cal features of rhabdomyoma include cytoplasmic than 2% of all striated tumours.5 Nearly 90% of positivity for muscle-specific actin, desmin, myo- adult rhabdomyomas are found in the head and globin, and myo-D1, while the immunoreactivity neck region, where they present as a solitary, slowly ­ for vimentin, S-100 protein, Leu-7, and smooth growing mass. However, approximately 3-10% of muscle actin varies.9 The differential diagnosis adult rhabdomyomas are multifocal.6,7 The most includes­ granular cell tumours, well-differentiated common sites are the floor of the mouth, tongue, rhabdomyosarcoma, extra-adrenal paraganglioma, palate, lips, cheeks, and larynx, and the parapha- and hibernoma. Differential diagnosis between ryngeal and submandibular spaces.4 Rhabdomyoma rhabdomyoma and rhabdomyosarcoma is of the usually affects people after the fourth decade of utmost­ importance. Rhabdomyosarcoma appears as life, with a male-to-female ratio of 3:1.8 Rarely, a rapidly growing mass, and it is usually associated rhabdomyomas have been found in the extremities, with pain and paresthesia. The histopathology esophagus, stomach, and mediastinum. of rhabdomyosarcoma includes the presence of The clinical presentation of rhabdomyoma usu- spindle or rounded cells, with very occasional ally includes a slowly growing, painless cervical cross-striations, and atypical nuclei. mass. The associated symptoms are dysphagia, Diagnosis by fine-needle aspiration (FNA) may hemoptysis,­ hearing loss, and hoarseness. In some be challenging, and granular cell tumours are com- cases, the tumour may be the cause of airway monly confused with adult rhabdomyoma. Both of obstruction­ and sleep apnea, whereas in about 10% these tumours have abundant eosinophilic granular of patients, the tumour is asymptomatic.­ 9-11 cytoplasm and round, bland nuclei that are centrally The microscopic features of rhabdomyoma are or eccentrically located.12 However, a correct diag- extremely characteristic, and mimic those of skele- nosis can be achieved if the cytopathologist is Rhabdomyoma of the pyriform sinus 79

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The characteristic microscopic ryngeal space: report of 2 cases and review of the litera- and immunohistochemical features of rhabdomyo- ture. Am J Otolaryngol. 2011;32(3):240-246. ma allow it to be easily differentially diagnosed Emmanuel Prokopakis, M.D. from other benign tumours. Total excision is the University Hospital of Heraclion cornerstone of treatment, and transoral laser resec- Building A, 3rd floor Voutes, 71500, Heraklion, Greece tion is an effective procedure in patients with rhab- Tel.: 0030-2810392347 domyoma of the hypopharynx. E-mail: [email protected]

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