Rare Adult Masseteric Rhabdomyosarcoma and a Review of the Literature
A previously healthy 32-year-old male nonsmoker presented at our ENT (ear, nose and throat) outpatient clinic complaining of a painless swelling in the right parotid region, which had been increasing for 2 months. The macroscopic examination reported a firm mass measuring about 3.5 × 1.5 cm with shaded limits, while ipsilateral lymphadenopathy was also present. No other ENT diseases were identified during the physical examination. The preoperative baseline parameters and chest X-ray were normal. Hematological and infectious diseases were evaluated, but both pathologies were negative based on hematological and microbiological examinations.\nThe patient was submitted to neck ultrasound, which identified a hyperechogenic nodular mass measuring about 2.5 × 1.3 cm in the right parotid region, with concomitant ipsilateral enlarged cervical nodes.\nMultislice computed tomography (CT) detected a mass in the right masseter with a maximum diameter of approximately 2.2 cm with central necrosis and perifocal inflammatory reaction, which was associated with thickening of the masseter muscle. At the lower parotid pole, there was a coexisting area of high enhancement, while multiple enlarged cervical nodes were found in the level III and IV cervical nodes, with a diameter of 1–1.8 cm (fig. , fig. ).\nMagnetic resonance imaging (MRI) with paramagnetic contrast identified an oval mass in the right masseter muscle, which was mildly hyperintense in T1-weighted images and hyperintense in long repetition time (TR), with regular margins and high contrast intake. The concomitant low pole mass had a cystic appearance with regular margins and low intensity in T1-weighted images and a higher intensity in short tau inversion recovery (STIR). Right lymphadenopathy was confirmed (fig. ).\nThe patient was also submitted to 18F-FDG positron emission tomoscintigraphy (PET), which indicated a high pathological increase in the glucose metabolism in the intramasseteric right region [maximum standardized uptake value (SUV max) 10.5], right jugular nodes, right submandibular nodes (SUV max 6.6), and right cervical nodes (SUV max 6.7). These were all suspected neoplastic locations (fig. ).\nSurgical treatment was proposed to the patient, and he gave written informed consent for treatment and case report publication. Ethical approval was received by the Institutional Review Board of ‘Magna Graecia’ University of Catanzaro, Italy. Thus, the patient was treated surgically by removal of the masseteric mass and by modified radical ipsilateral neck dissection. During surgery, the tumor appeared irregularly limited and it was strongly adherent to the mandibular bone surface and the masseter, with a colliquative lower pole. Postoperative tests were regular and the patient was discharged on the 5th postoperative day.\nHistological examination identified alveolar RMS in the right masseter mass and 44 cervical nodes (superficial periparotid node, intraparotid node, and levels IIA–IIB–III–IV–V right cervical nodes), with small and intermediate-sized round tumor cells according to hematoxylin and eosin stain (fig. ) and widespread nuclear immunoreactivity to myogenin (fig. ).\nThe tumor was classified according to the Intergroup Rhabdomyosarcoma Study (IRS) postsurgical pathological system as Group IIa (table ).\nThe patient received radiochemotherapy with radiation at 45 Gy, while chemotherapy consisted of 14 cycles of vincristine, dactinomycin, and cyclophosphamide (VAC).\nThe patient received a strict follow-up protocol with 3-monthly checks. He was free of locoregional disease with no evidence of distant metastasis 1 year after diagnosis.