BACKGROUNDSystemic lupus erythematosus (SLE) is a chronic autoimmune disorder, characterized by alternating disease activity and remission, often affecting young women, in a 9:1 ratio. Cutaneous lupus affects the skin and mucosa, and lesions in the oral cavity are varied, such as canker sores and ulcers. SLE is associated with a higher risk of developing neoplastic transformation, whose mechanism is still poorly recognized; however, it is suggested that disease activity and prolonged use of immunosuppressive therapy are important triggers. There are few cases of squamous cell carcinoma (SCC) reported in the literature, especially in the oral cavity. The report describes a case of SCC in the tongue diagnosed in a patient with SLE. CASE REPORTA 26-year-old female patient undergoing regular follow-up at a tertiary hospital rheumatology outpatient clinic, diagnosed with SLE in 2011, associated with antiphospholipid syndrome (APS). She was diagnosed with human papillomavirus (HPV) infection in 2020 after colposcopy, which showed lowgrade squamous intraepithelial neoplasm. At the time, she received treatment with laser therapy and maintained remission, with routine consultations with gynecology. In 2021, she developed an ulcerated lesion on the right lateral surface of the tongue, whose pathology study showed a well-differentiated, invasive, keratinizing SCC. She underwent right hemiglossectomy, with lymphatic dissection of the homolateral cervical chain, protective tracheostomy and tongue graft, followed by 30 sessions of radiotherapy. The graft was lost, however, therapeutic success was achieved, evidenced by free margins in the anatopathological sample and the absence of distant metastasis. CONCLUSIONSLE is a potentially malignant condition and there are few reports in the literature of association with oral SCC. Oral ulcerated lesions are common in SLE; however, it is important to consider malignant transformations, as in the case above. The attending physician must be aware of this possibility, taking into account clinical suspicion and early identification of cases, in order to obtain better outcomes.