ADULT RHABDOMYOMA OF THE ORAL CAVITY

This report describes a case of adult rhabdomyoma (AR) in the oral cavity. A 47-year-old male was referred for diagnosis of a painless lesion located in floor of the mouth, with 2 years of duration. Intra-orally, the lesion appeared as a large, well-delimited swelling mass measuring about 5.0 cm, projecting the tongue superiorly and posteriorly. On computerized tomography examination, there was a well-delimited, solid, hypodense mass. The main hypothesis of diagnosis was a salivary gland tumor. The patient was submitted to surgical excision. Microscopically, the nodule was composed by large polygonal cells with well-defined borders, which exhibited abundant, eosinophilic, and granular cytoplasm. Cross-striation in the cytoplasm was also observed, and there were no atypia or mitoses. The cells were positive for muscle-specific actin, desmin, and α-sarcomeric actin. Calponin, h-caldesmon, and myogenin were negative. Based on these features, the diagnosis of AR was established. No recurrence was observed after 24 months.