CLASSIFY-OMM: Multicenter Rare Disease Cohort for T-Stage Reclassification and Molecular Subtyping-Based Precision Therapy in Oral Mucosal Melanoma

Inclusion Criteria: * Histopathologically confirmed primary oral mucosal melanoma (WHO criteria); Primary site: oral mucosa (palate, gingiva, sublingual, buccal, hard palate, floor of mouth); Receiving or planning standard treatment (surgery, radiotherapy, chemotherapy, immunotherapy, or targeted therapy); Age ≥18 years, any sex; Complete clinical data with pathology, imaging, and records (retrospective) OR willingness for long-term follow-up (prospective); Signed informed consent (prospective) or data meeting ethical waiver (retrospective). Exclusion Criteria: * Primary melanoma originating from skin, eye, esophagus, or other non-oral mucosal sites; Secondary/metastatic oral mucosal melanoma (primary not in oral cavity); Unavailable key clinical information (surgical records, pathology, imaging); Prior or concurrent other malignancy interfering with prognosis; Severe mental/cognitive disorders or poor compliance; Severe comorbidities (heart failure, liver/renal failure) affecting treatment or survival analysis; Patient refusal or withdrawal of informed consent.