Clinicopathologic study of the adult rhabdomyoma in the oral and maxillofacial region

Objectives This study aimed to explore the clinicopathological characteristics of adult rhabdomyoma (A-RM) in the oral and maxillofacial region. Materials and Methods We analyzed seven cases of A-RM in the oral and maxillofacial region, focusing on the clinical manifestations, imaging findings, histopathological features, differential diagnosis, treatment, prognosis, and relevant literature review. Results The age range of the seven A-RM cases was 4 to 83 years old. Six cases were male and one case was female. Three cases occurred on the floor of the mouth and one case on the tongue. All A-RM cases presented as slow-growing, painless masses. The lesions were lobulated, red-brown nodules with well-defined margins. Histologically, they consisted of densely packed, large, round and polygonal cells with abundant granular eosinophilic cytoplasm. Cross-striations and vacuoles were observed in the cytoplasm. Tumor cells were positive for desmin, myoglobin and myogenin, and some tumor cells were positive for SMA, MyoD1 and S-100 protein. PAS staining was also positive among tumor cells and could be digested by diastase. Conclusion Histological examination is the main diagnostic criterion for A-RM. The detection of cross-striations and immunohistochemical expression of myogenic proteins in the cytoplasm are crucial for accurate diagnosis. Radical resection is the main treatment modality with generally favorable prognosis.