Gingival rhabdomyosarcoma mimicking a non-neoplastic proliferative lesion: A diagnostic challenge

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma that develops from skeletal striated muscle cells. RMSs are exceedingly rare in the oral cavity, particularly in the gingiva. Herein, we reported the clinicopathological and immunohistochemical features of a rare case of RMS in a 30-year-old female presenting clinically as a painful polypoid nodule on the mandibular gingiva. Microscopically, the tumor showed atypical spindle cells with elongated nuclei and eosinophilic cytoplasm arranged in a fascicular pattern. In focal areas, the tumor cells exhibited rhabdomyoblastic differentiation. Immunohistochemistry showed strong positivity for desmin, myogenin (scattered cells), and MyoD1. The patient underwent surgical resection followed by postoperative complementary radio- and chemotherapy. However, the patient had a local recurrence seven months after the initial treatment. She was submitted to a total mandibulectomy associated with adjuvant radiotherapy. However, she died two months after reoperation due to complications secondary to radiation therapy. Because of the rarity in the oral cavity and non-specific signs and symptoms, the clinical diagnosis of RMS is difficult and often overlooked. Therefore, careful histopathological and immunohistochemistry analysis of these tumors is essential to correct diagnosis. Early surgical excision with tumor-free margins and prolonged follow-up are strongly recommended.