Giant Sublingual, Submental, and Lingual Dermoid Cyst Restricting Tongue Movement Undiagnosed for Several Years

(1) Background: Dermoid cysts occurring in the sublingual space are uncommon, typically manifesting as painless, gradually enlarging masses, usually not exceeding 3 cm in diameter. These cysts can resemble various conditions due to their clinical presentation, with a relatively low occurrence rate in the oral cavity, accounting for about 1.6% of all dermoid cysts. (2) Methods: We present the case of a 17-year-old female with a giant dermoid cyst involving the submental, sublingual, and lingual areas, undiagnosed for several years. Diagnosis was achieved through MRI and fine-needle aspiration, leading to the decision for surgical removal through a cervical approach. (3) Results: The healing process was uneventful. From the first day post-surgery, the patient began myofunctional therapy, successfully regaining proper tongue functions. Throughout a 24-month follow-up, the patient remained symptom-free. (4) Conclusions: A cervical approach can successfully treat giant oral dermoid cysts involving submental, sublingual, and lingual spaces. Tongue function can be successfully regained through myofunctional therapy after surgical treatment.